1. Syracuse University Project Advance CHM 113 Forensics

2. Forensic Science – can be thought of as the point where the legal system and scientific inquiry intersect. The law wants certainty – while scientists can only provide probability, data and facts. Science provides information regarding the odds that two events will occur in a specific way. Different evidence demands different analysis techniques and tests. Each have a different error rate. -Forensic Odonotology vs. DNA

3. Example: DNA analysis can tell us what the odds are that there will be a DNA match between unrelated and random samples. The odds are 1 in 5 trillion that two unrelated people will have the same pattern within their DNA. All we can do is provide the information and facts. It is up to the jury and judge to decide whether our information and error rates are enough to prove beyond reasonable doubt.

4. The technical information that we provide a jury can sometimes cause problems. The jury may not always be knowledgeable enough. More importantly, the jury has to be able to differentiate between real and pseudoscience. What type of scientific evidence is admissible is determined in two major ways.

5. Up until 1923, each judge decided what evidence was admissible regarding scientific testimony. There was no standard that evidence had to match up against in order to be allowed in court. Meaning, real scientists and laypeople with little to know understanding could both present their testimony to the judge and jury. What scientific evidence is admissible?

6. There are two major standards that courts in the United States use today: Frye and Daubert. More on these later, these two cases set legal precedents regarding what scientific evidence, analysis and interpretation could be deemed admissible. Scientific Evidence Standards

7. Forensic science encompasses disciplines from across the board – chemistry, biology, physics, anthropology, psychology, ballistics, medicine. Each of these areas have their “experts” that will handle evidence that pertains to their area of knowledge.

8. Instead, each expert provides a thread and the primary investigator from law enforcement weaves all the threads together to understand the who, what, where, when and why.

9. Because the terminology and knowledge is often more technical than a jury or judge can truly understand… forensic evidence is hardly ever eliminated from use. Forensic testimony provided by experts is often looked at as foolproof regardless of the error rates. Are there any drawbacks to forensic evidence?

10. Due to the popularity of TV shows like House, Cold Case, CSI, Law and Order etc, juries are now almost requiring there to be scientific evidence provided at every trial. Even if there is no doubt a suspect was present at the scene of the crime (because he confessed to being there), juries are looking for forensic evidence to link him/her there. The CSI Effect

11. Without forensic evidence, a jury will often feel like it is a “weak” case and may be less likely to convict. More and more often, experts are brought in just to explain to the jury why forensic evidence is NOT necessary for certain situations. Testing and analyzing each piece of evidence for petty crimes such as shoplifting is an expensive mismanagement of resources, time and money. The CSI Effect

12. Defined as the application of scientific methods and principles to the investigation of crimes and criminals. It is considered an applied science because the science answers questions in the real world – particularly of the legal variety.

13.  The term “forensic” comes from the Latin “forum”. The forum was used in ancient Rome to seek justice.

14. The first known use of forensic evidence was the use of fingerprints to identify cave paintings and pottery in the BC era. In ancient Greece, Archimedes used forensic evidence to investigate fraud related to the gold crown that was commissioned by Hiero.

15. The first forensic textbook was published in 1248 by Sung T’ze – a Chinese magistrate. The book collected historical cases, and information regarding procedures for conducting autopsies, collecting and interpreting evidence. First recorded use of forensic entomology.

16. Entomology is the study of insects. Forensic entomologists study insects and other arthropods to aid in legal cases. Insects, particularly blowflies, maggots and beetles can provide of the most reliable data on time of deathsome. Forensic Entomology

17. Fast forward to the 1800s – major developments in blood testing, chemical testing, ballistics and fingerprints. People began looking at fingerprints and recognizing that they could be classified due to similar patterns. Fingerprints began being used for simple identity verification. The idea that you could use physical characteristics to identify people began to be accepted by the general public. Prior to this, many law enforcement agencies relied heavily on eyewitness testimony which is not reliable.

18. Besides fingerprints, there was another physical trait analysis developed by Alphonse Bertillon. This is called anthropometry.

21. One of the major problems with Bertillon’s methods was often when two officers measured the same suspect – they would come up with different measurements. Other complications include how physical features change as we age. If a crime was committed several years ago – the measurements may change.

22.  Another contributing factor to the decline of the Bertillon measurements was how quickly fingerprint identification was advancing.

23. More major developments: Locard’s Exchange Principle He believed that when two objects come in contact with one another, there is an exchange of physical matter. If you can find that exchanged material, then you can prove the two objects touched each other

24. Common examples: Finding a victims blood on a piece of clothing found in the suspects apartment. Finding a fiber from a cotton shirt in the trunk of a car that matches the fiber from the victim. Other examples? The hardest part is finding what has been transferred between the two objects.

25. Other contributions made by Locard: He also believed that in the heat of the moment, a criminal would “undo” themselves. In other words, during the stress of the crime – the criminal would make a mistake that would lead to his arrest. May 2010 – Terrorist Bombing in Time Square

26. Forensics and Popular Literature and Culture: 1887: Sir Arthur Conan Doyle created the detective Sherlock Holmes. His methods inspired many areas of criminal investigation although he was fictional. Holmes was a pioneer in the field of crime scene investigations and was actually inducted into the UK’s Royal Society of Chemists.

27. Sherlock Holmes used fingerprints before they were ever used in real investigations and had a manuscript that identified 140 types of tobacco by their ashes. As he used these “advanced” techniques, law enforcement agencies moved towards these new technologies to assist them in their own investigations.

28. “The process I said starts upon the supposition that when you have eliminated all which is possible, then whatever remains, however improbable, must be the truth”

29. Locard: Glass shards, pollen, DNA found on suspects clothing can link them to a crime scene if the crime scene has the same material / objects. Also works the reverse – if you find fingerprints, semen, blood from the suspect at the crime scene – it also proves they were there. Fundamental Principles

30. Principle of Individuality: Even though two objects may appear identical and indistinguishable, they can never be exactly the same. We might not be able to tell the difference with the naked eye - but at the atomic, molecular level, they must be different.

31. For example: two bullets are made by the exact same manufacturer but when they are fired from a gun – there are distinct differences to identify the two different bullets. Key Point – we have to have the technology to find the difference.

32. Important Cases: Legal Precedents Precedent Cases are said to “carve a pathway through the legal forest so that future cases may travel smoothly” They are used as guides and often dictate decisions in the future. They are often used to take written law and figure out how it applies to real world scenarios. Courts will try to stand by answers to legal questions that have already been answered by a previous verdict.

33. Legal Precedents as the apply to scientific testimony and evidence: Courts don’t always know what good science is, so they need to be protected against improper, incorrect or misleading testimony. As we become more and more technologically advanced, the gap between what the scientist knows and what the general public understands is going to widen. It is critical that only good, reliable, reproducible scientific testimony is admissible in court.

34. 1923: The Frye Case James Frye was accused of murdering Dr. Brown and initially confessed. Prior to going to trial, Frye took back his confession. In an attempt to prove his innoncence, Frye’s lawyer had him take a very simple lie detector test. During questioning, his heart rate and blood pressure were measured and recorded to see if there was any changes during “high stress” questioning. James Frye passed the lie detector.

35. The judge ruled that the lie detector test and results were inadmissible on the grounds that the test lacked scientific validity and was found guilty. He appealed the verdict and the case made its way to the Federal Court of Appeals The appeal failed and the decision to not allow the lie detector was upheld. This was the first precedent set about scientific evidence in a legal setting.

36. The appeal court decided that: courts will go a long way to admit expert testimony from a well recognized scientific principle. However, the principle must be sufficiently established and have support from the field. In addition, this extended to scientific testimony. Scientific testimony was only admissible if the person testifying is considered an expert in their area.

37. Finally – courts were given guidance on what techniques had been established and underwent rigorous reproducibility inspections. Techniques needed to be published and accepted by the scientific community. Major drawback: The Frye Standard for what is admissible forensic evidence is a very slow process.

38. About half the states use the Frye standard currently, including New York. As science and technology advanced, the courts were having a hard time keeping up with forensic evidence and a new standard was established. In the 1990s, in response to ever changing technology, a new standard was established: the Daubert Standard.

39. 1993: Daubert vs Dow Trying to prove that a drug Bendectin produced by Merrell Dow Pharmaceutical Company, was causing birth defects. Dow argued that the plaintiffs didn’t have a case because the experts that were brought in could not produce a published paper linking bendectin to birth defects.

40. The Daubert experts said that there was a link, but it was based on new methods that had not been accepted by the scientific community yet. The court ruled in favor of Dow, based on the Frye standard. The case went to appeals and was reversed under the following:

41. “ If scientific, technical or specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue – a witness qualified as an expert by knowledge, skill, expertise, training or education may testify thereto in the form of an opinion or otherwise.”

42. The major difference between Frye and Daubert is that scientific evidence and expert testimony does not require acceptance by scientific community to be admissible. Instead, it relies in 3 standards for admissibility: A. Scientific Basis: must be grounded in scientific knowledge gained through the scientific method. Must have sufficient data or fact, reliable methods, properly carried out protocol.

43. B. Relevance: testimony must assist the trier of fact (judge or jury) in deciding the issue. Must be a connection with knowledge and the issue. C. Judge is the “gate keeper” – the judge decides whether the testimony is sufficiently established and relevant. The judge determines whether the methodology or reasoning is valid.

44. The judge relies on the scientific field to determine - has the theory been tested - is it subject to peer review - what is the error rate - are there standards controlling the performance and analysis - has it received widespread acceptance.

45. The Daubert standard is used in all federal courts and half the states. It is much more flexible in admitting new evidence. Alec Jeffries discovered that DNA could be used to identify people in 1985. This took 18 months to make its way into being admissible into court under the Frye Standard.

46. Khumo Case: 1999 The plaintiff was suing the Khumo Tire Company, claiming that a tire blowout and accident was because of a defective tire. The expert for the plaintiff relied on a method that was not scientifically valid or even tested prior. This extended the Daubert standard to not only forensic scientists, but any skill or experience based testimony. The expert must have a level of intellectual rigor that would match the practice of another expert in the field.

47.  This extended the Daubert standard to not only forensic scientists, but any skill or experience based testimony. The expert must have a level of intellectual rigor that would match the practice of another expert in the field.

48. Melendez Diaz – 2009 Drug case – the prosecutor introduced a chemical analysis of a white powder that was found to be cocaine. Analysis was performed by a lab tech under standardized protocol. Defense argued that the actual lab tech is the person who should state that the white powder was cocaine, under the pretense that the defendant has the right to face his accuser. This means that whoever runs these tests, must be the person to actually present their results in court. This is still tied up in court and is under review.

49. Evidence is used to connect two things suspected to be involved in a crime. Examples – connecting a weapon to wound, suspect DNA with crime scene etc. The evidence that we are looking for is the exchanged material from Locard’s principle. Chapter 2: Physical Evidence

51. Types of Evidence: Physical evidence includes material objects such as a shell casing, item of clothing, tire tracks, bloody weapon. Other types of evidence found and analyzed by forensic scientists include but is not limited to: cyber, chemical, biological, linguistic and behavioral.

52. Why collect evidence? Evidence can serve two main purposes in crime scene investigation: 1.Identification Analysis 2.Comparison Analysis

53. Identification Analysis: Describes the item in detail by identifying distinguishing features and characteristics. Include specific and certain details so that they item can be identified without doubt. For example: Describing the striations on a bullet which are unique patterns from the gun.

54. Comparison Analysis: Compare an item found at the crime scene with a standard or known to find a “match”. You are trying to determine if the exemplar (evidence) and the standard came from the same source. Example: Finding a hair at a crime scene. You would conduct comparison analysis to determine if the hair came from the suspect. Most often used for DNA and fingerprints.

55. When using comparison analysis for DNA or fingerprints, there are two methodologies. The first type is a “one to many” matching. You match your exemplar or unknown to a large pool of candidates for a possible match. This is similar to running fingerprints through a database to see if there is a “hit.”

56. One to Many continued. This can also be used to identify white powder. You would compare the spectra that you collect to the known spectra of hundreds of white powdery compounds to see if there is a possible match. One to Many often relies on pre-established databases and computers to provide the large pool of possible matches. Databases include handgun firing pin patterns, DNA profiles, chemical spectra, fingerprints, eye iris patterns.

57. Gas Chromatograph of Cocaine

58. Mass Spec of Cocaine

59. The other type of comparison analysis is called Verification or Authentication You compare a set of features observed in an unknown to a reference sample or standard. For example, an ATM using the fingerprints of the person trying to access the account to the standard in their system – before granting access. Doing an eye iris scan on people to compare them to a suspects eye iris scan pattern, you are comparing the unknown people to a standard – your suspect.

60. Both of these analysis methods reliability depend on matching as many features as possible. -Matching 2 points on fingerprints will only narrow a large pool of people. -Matching 13 points on fingerprints, narrows the pool down to a very low possibility that the fingerprint would come from another person.

61. DNA evidence is often matched by examining different loci (places) on chromosomes for Short Tandem Repeats (STR’s). Each person has a unique number of STR’s in certain regions of the chromosome. Matching 2 loci for their STR will give 1 in 500 odds that the samples are from the same source. However, matching 13 loci give a 1 in 7 trillion odds. Much more reliable.

62. Class Characteristics: they are features of the item that will place it within a group. It’s a way of general sorting evidence. Determining that blood is AB blood, the weapon is a lead pipe, the make and model of the tires on the car, fiber from a cotton t-shirt. This is especially useful for blood evidence. By typing the blood, you can narrow your search pool. The percentage of people with AB- blood is 0.7%. Characteristics of Evidence

63. Guess Who?

64. Class characteristics are not often used to establish the link between two items, places, people. Instead, class characteristics are used to narrow the scope of your search and focus your efforts. The more class characteristics you have, the smaller your pool becomes and the easier it is to find what you are looking for.

65. Imagine playing the game “Guess Who”.. You would guess whether the person had glasses. If they had glasses, your opponent would known down everyone who did NOT had glasses. This narrows down the possibility. Then you might ask about hair color, eye color, height, left handed or right handed. It is a way of classifying people into groups and narrowing your search. It can be used for other types of evidence, such as shell cases, bullets, blood, fibers, glass etc.

66. Individual characteristics are a way of recording details that make an item unique and easily identifiable. Scratches on a fired bullet, fingerprints left on a door handle, matching patterns on tire tracks, matching loci on DNA evidence. Individual characteristics usually provide the final link between two objects.

67. It is rare to use one type without the other. Most often evidence is first classified using class characteristics, and then scrutinized for individual characteristics. Example: Tires can first be classified into groups for the model, color and size. Then the tire tread can be matched with the details on the tire track to place the tire at the crime scene.

68. Example: Glass is found at a crime scene. First, the glass will analyzed for class characteristics to determine that it came from a windshield. Then shards of class will be analyzed for their individual characteristics, until a shard of class may fit a wound on the victim. This will provide evidence that the victim went through the windshield.

69. Before evidence can be examined and characterized, their must be proof that the evidence was seized and collected in the appropriate fashion. “A man’s home is his castle” – meaning people cannot invade your home, search and seize evidence without just cause and a warrant.

70. A warrant must be granted unless it is a special circumstance prior to law enforcement searching and seizing personal property in connection with criminal or illegal investigations. UNLESS YOU CONSENT. Warrants must outline specific goals, what you are looking for and why. Warrants are not given unless law enforcement has provided probable cause that they will find the items they are looking for within your personal residence, car etc.

71. Search warrants are issued by a judge and give officers the authority to search a specific place, at a specific time, for a specific reason. To prove probable cause, officers will often present previously established evidence or facts to the judge to support why they are looking for the items on the warrant.

72. Warrants only allow officers to search within places listed on the document and take items listed. For example, if they are looking for a stolen car, and find the car, they are not allowed to begin looking inside compartments in the car. Because a car could never fit inside the glove compartment. However, if keys are listed on the warrant – then then the glove compartment is fair game because keys would logically fit in the glove compartment.

73. When are warrants not required? Police officers do not need warrants to search or seize anything that is plainly visible from a place that they would ordinarily be standing. This is known as the plain view doctrine. In your own home, you have a legitimate expectation of privacy, however if illegal activity is occurring in front of a ground level window – that is in plain view- officers may enter without warrant.

74. Items in plain view do not fall under the 4 th amendment. If you get pulled over and there is a gun on the floor that is in plain view, no warrant is necessary to search and seize personal property.

75. Other exceptions: - You give consent. Only adults with some measure of control or responsibility for the space can give consent. You can consent to have your apartment searched, but they may not search your roommates property since that is not under your control. They may only look in shared, common spaces.

76. -Legal Arrests – if you are arrested police officers may search and seize evidence, even if you were incorrectly arrested. -This includes your car, home or property. These searches may only be a sweep to make sure that there is no immediate danger.

77. -Emergency Circumstances Warrants are not required to enter a smoke filled building and search for people. Not required when chasing a fleeing suspect “in hot pursuit”, during an emergency call or if they see evidence being destroyed. The Supreme Court ruled that during a traffic stop for a DUI, officers may force you to take a BAC test because your body is destroying evidence as you metabolize the alcohol. Failure to comply automatically results in a suspended license.

78. -Airports, border, sea: personal body scans, baggage scans without warrants. -Stop and frisk – if officers believe something illegal occurred or is about to, they can pat down and frisk a person. Anything found may be seized. -National Security – Patriot Act: email, bank statements, financial and medical records can be searched without warrant.

79. Administrative searches: electrical, safety inspectors may search a residence however cannot collect specific evidence. They can alert authorities who can then request a warrant. Inventory searches: If they are searching a boat or car, they can take inventory to protect the person’s property to protect officers from false claims of items being damaged or going missing. If anything illegal is found, they may seize

80. Important Cases: Mincy vs. Arizona A drug bust led to the death of an undercover officer and wounded the suspect. After a quick search that would qualify as an “emergency call,” officers spent 4 days collecting nearly 300 pieces of evidence in the apartment. The US Supreme Court ruled that none of the evidence collected in the first 4 days was admissible in court. The detailed search required a warrant, because the “emergency” situation did not last 4 days. Key Idea: Emergency searches can only last for a certain amount of time.

81. Michigan v. Tyler: Arson investigation after a fire occurred in a furniture before midnight. After the fire was put out at about 2 am, fire and arson investigators began searching until 4 am. Investigators returned for the next 3 weeks and Tyler was convicted of arson. Supreme Court ruled again that the evidence was not properly collected. Clearly the emergency did not last for 3 weeks. Also – the crime scene was not properly secured at night and easily accessible, leading to possible evidence tampering.

82. Processing a crime scene: To ensure that the evidence collected with an appropriate warrant is admissible in court, it is important that a crime is processed by following guidelines and protocols. This involves: securing the scene, recording the scene, searching and collecting evidence and packing/transporting evidence.

83. Securing the scene can be challenging, particularly when there are injuries or fatalities. The first priority is to make sure the scene is safe and that medical assistance has been provided. The first responders assume that there is still a crime in progress until proven otherwise. They should note anyone leaving the scene, potential suspects, and anything out of the ordinary.

84. EMT and police will cooperate to ensure that both may conduct their work. Medical treatment always takes precedence over evidence collection. The officers will assist the EMT by writing down if the EMT moved any evidence, moved people. It is important that the EMT never “clean up” their mess due to Locard’s exchange principle. By cleaning up, they may remove trace evidence that could be critical to the case.

85. Once the scene is secure, the responders must isolate the scene. They establish a large perimeter to encompass the whole scene and get any unauthorized personnel out of the crime scene. As these unauthorized people are moved out, they should also be isolated for questioning.

86. After a large perimeter has been established, the lead investigator will determine the crime scene boundary and section it off with police tape. Typically, the crime scene boundary is made larger to try to preserve evidence that may not be immediately visible. It is always better to have too much space to cover, then to have too small a crime scene. Any evidence outside the boundary may be destroyed by environmental factors, or taken away as part of the “clean up”

87. After the police tape is up, it is critical that the people allowed in and out is carefully monitored by a gatekeeper. The gatekeeper will record who and when people enter and leave the crime scene.

88. Recording the Scene: Complete documentation: location, condition and appearance of people and objects, weather conditions. In order to create a map of the crime scene, we have to understand where objects are in relation to one another. This is often done with a technique, known as triangulation.

89. Triangulation: -Two fixed points are selected in the crime scene, such as a light pole and a fire hydrant. -The distance from each object in the crime scene to each fixed point is measured. -This fixes the position of the object in relation to two other things that will not move.

90. Other methods to mapping the scene: Azimuthal locating: Instead of measuring distances from two fixed points, you measure angles from the object to fixed points. Coordinate Mapping: Divides the crime scene into squares like a bingo card. The contents of each square are then searched, mapped and recorded. Electronic Method: Using GPS to map a crime scene and then using software to take that information and transform it into a 3D crime scene.

91. The measurements and the identity of objects create a detailed map of the scene. The rough sketch is transformed into a detailed map that can be 2D or 3D using CAD software.

92. CAD SOFTWARE EXAMPLES

93. Crime Scene Photography: Photography is only one way to record the scene, used with field notes and detailed maps. -Overview photos are first taken, to preserve scene as you saw it -Pictures should start from outside and work inward. Overview shots should include all entrances/windows. -Discuss scene with police to determine what type of photography

94. Indoor photos should be taken in the same manner that you enter the crime scene. Be sure to include walls, and any other rooms/areas connected. Finally, evidence photos are taken: - Show how item is positioned in relation to surroundings. - 2 nd photo should be details and markings - Take two photos of each piece of evidence - One of evidence alone - Other with measuring device (ruler) to show scale

95. Search and Collect Evidence Once the site has been secured, mapped and photographed – Search Begins There are several different patterns that may be used to search, depending on different situations.

96. 845 square miles of Crime Scene. 10,000 pieces of evidence found, collected, package and stored. Lockerbie Bombing Crime Scene

97. Search Patterns:

98. Extensive protocols exist – see handout Examples: Volatile materials, liquid, powder, controlled substances belong in airtight containers DNA/Biological evidence: Package in material that will allow airflow, for sample to dry in the most natural way possible. Always paper, never plastic. Evidence Collection and Preservation:

99.  Goals of Evidence Packaging:  Prevent any change in the item  Prevent cross contamination with other samples  Preserve sample as intact as possible  Safe environment  Proper Identification, Chain of Custody information

100. As evidence is transported and stored, each piece of evidence must have a record of who handled it, when it was handled. The Chain of Custody (CoC) is a chronological documentation from when it was found all the way to when it was presented in court. The idea behind CoC is to prove that evidence had not been tampered with and was indeed found at the crime scene.

101.  Details found in the chain of custody include: what is done to the sample, where it was stored, when it was transferred, who transferred, who controls the evidence.  This creates a record of every moment and movement in a piece of evidence’s “lifetime”  If the CoC is broken, that piece of evidence will not likely be very useful in court.

102.  When is a Chain of Custody not required? Certain pieces of evidence do not require a CoC because they are so unique: objects with serial numbers, VIN, license plate numbers all found at the crime scene.

103. Often, crime labs will have evidence teams that are sent to crime scenes. Each member of the team has a specific job: Team Leader: Determines boundaries, search method and coordinate with other personnel. Must constantly reevaluate as scene changes, as new evidence is found. They are also responsible for the final release of the site back to the owners.

104. Photographer: Documents whole scene and each object before it is collected. Continues while evidence is collected. Make sure a scale marker is in each photo. Scale marker can be a ruler, coin etc. Something to use as a reference.

105. Before photos are taken, they must be recorded in a log so they can be easily identified and used at a later date. The log must include the date, time and item being photographed to be used to “weave” the scene together at a later date.

106. Sketch: A detailed map is constructed that includes the location, measurements of evidence. Begin with a rough sketch: shows dimensions, orientation and location of evidence. Use computers later to create final sketch.

107. Evidence Recovery and Recorder: Search, locate, collect and package. 1.Log and Photograph each piece. 2.Recorda description of item and label. 3.Begin the CoC as they give it to delivery.

108.  Specialists: Certain crime scene require specialists. Anthropologists may be needed for skeletal remains, DNA technician for biological samples.  **The entrance and exit of these people into the crime scene must be closely monitored and recorded.

109. Three Types of Crime Scenes: Outdoor: Most difficult because evidence is open to environmental conditions. Very easy for evidence to be destroyed or degraded. Must be processed quickly. Indoor: Easier to control, but more difficult to coordinate all of the personnel in a smaller space. Conveyance: Any crime scene that occurred on some form of transportation.

110. The Frye and Daubert standard work towards eliminating junk and pseudoscience from the courtroom. Remember, before 1923 – each court decided on its own what was considered good science. Today, as technology advances – we must constantly re- evaluate what is reputable science and how to disseminate that information to juries and judges. Chapter 3: Pseudoscience and Ethics in Forensics

111. Conflict: judges and juries want definitive answers and science can only prove simple facts. Under Daubert - science was defined: A process for proposing and refining theoretical explanations about the world that are subject to further testing and refinement. Proposed testimony must be supported by appropriate validation. ** Refined is especially important today, as technology advances rapidly **

112. Scientific testimony is rooted in the scientific method 1.Observations – describe and quantify. The measurements taken depend largely on the area of expertist that is handling evidence. Usually after crime is committed. 2.Hypothesis: Formulate a hypothesis that is supported by the data (evidence). Should lead into new investigations and data collection. These are your possible scenarios. 3.Prediction: How are you going to test its validity – how will you use new evidence to support original hypothesis

113.  4. Experimentation – use best standard practices and protocols to eliminate errors and bias. Always repeat and let others redo. During experimentation – very important that if data is collected that doesn’t fit with hypothesis – it cannot be eliminated. The outliers are the most useful for you to go back and try to reevaluate and make sense of evidence. Forensic science wants to find the limitations, and be open to as many possible outcomes.

114. 5. Analysis and Refinement or Abandonment of hypothesis: If data supports, then more in depth studies are pursued. If data refutes, then process begins again. Investigators should always look for data that disproves or disagrees with their hypothesis. Otherwise, they may miss out on a conviction. From a legal standpoint – step 5 is the endpoint, this is when a judgement is rendered. However, in science – things are always retested and refined.

115. Occam’s Razor and Pseudoscience: When you have two competing theories, that make the same prediction – the simpler the better. You “shave away” assumptions to simplify… the cleaner the better. Pseudoscience often relies on confusing jargon, terminology, and complex explanations to confuse people. This often intimidates people, so they believe it must be real science.

116. Telltale features of pseudoscience: 1.Exaggerated or untested claims without any data. Claims are often too broad, too good to be true. 2.Relies on hearsay, anecdotes as proof 3.Only include tests that provide data that confirms their claim, ignores test that disprove 4.No concrete evidence, relies on false authority – like TV s stars as experts. 5.Lots of new terminology/ technobabble to confuse and mislead. True scientific testimony should be clear, concise and understandable. 6.Static, never revisits ideas. Real science is always refined and changing.

117.  Comparing Science and Pseudoscience:  Publications: Science articles are reviewed by experts, subject to rigorous editorial and experimental controls. Pseudo: brochures, flyers, books.  Reproducibility: Must be reproduced by other scientists, disclose full procedures. Pseudo: details about methodology often not disclosed  Claims: clear, supported by evidence and accepted by other scientists in disciplines. Pseudo: vague, no backup

118. Support: evidence based claims, full transparency. Pseudo: anecdotal and misleading. Revision: constant updates, abandoned as new data is available. Pseudo – rarely changed. Experimental Plan: look for failures or limitations. Pseudo – designed only to confirm. Contradictory Evidence: include and then revise. Pseudo: throw out Future: looks forward to gain more understanding. Pseudo – no further insights.

120. Statistics and Probability in Forensic Science Math is used to quantify and strengthen how “trustworthy” forensic evidence can be. Courtroom has become increasing reliant on math to render evidence useless or convince a jury it is infallible. Statistics – focus is placed studying a sample to make conclusions about a large population. Interpretation and validation of data. Probability: Learns about a sample by studying the large population. Likelihoods of events will occur.

122. Probability Given Model, Predict Data Statistics Given Data, Predict Model

123.  Statistics: all measurements come with variability or uncertainty. Every time we measure an object, there is a chance it will change slightly.  Statistics is used to quantify that variability. The bigger the variability, the less trust we place in that measurement.

124.  Important terminology a you should already know:  Mean, Mode, Median, Distribution

125. Standard Deviation: Provides information about the distribution of data points in a set or how often each data point appears. Standard Deviation tells us what the distribution looks like and quantifies the variability within a set of data. Also provides an indication of confidence

126. One SD extends from the median contains 68% of data, 2 SD should contain 95% of all data.

127.  Standard Deviation (SD) measurement of variability  A small value for SD means data points are clustered around median, while large SD usually is a flat curve.

128.  Calculating Standard Deviation

129. 1.Calculate the mean for your data points 2.Determine the difference between the mean and each data point, and then square the difference 3.Add them all together 4.Divide by “n” – your # of data points 5.Take the square root.

130. Example: A set of data has the following values: 2, 3, 3, 5, 5, 7, 9, 9, 11, 11, 12 1.Determine the mean. 2.Determine the difference between each point and the mean, and then square it. 3.Divide by “n” 4.Take square root Answer: 3.4

131. Error Bars: Standard deviation information placed directly on graph, around each data point - to give an indication of the variability around each point.

132. Frequency: The amount of times a given measurement shows up in a set of data Range: The difference between the highest and lowest value in a set of data

133. Q test: When data points look like an “outlier” or far enough from the rest – we can do a q test to justify ejecting that data point from the set. Because we don’t always know whether an instrumental or human error occurred, it is impossible to justify ejecting a data point just on a hunch. Works best for sets that contain 3-10 data points, which is usually fine for forensics. If you have more points than you might use the Grubb’s Test (G test)

134. Formula: Where: x nearest: data point closest to disputed x0: data point in question x max and x min: largest and smallest in set

135. After Q is calculated, it is compared to a critical table of Q values for different data sets: If calculated Q is less than the table: the disputed data point must be kept in the set. If calculated Q is greater than the table: disputed data point can be excluded.

137. Example: The following measurements were colllected 9.1, 12.3 and 12.4. It looks as is 9.1 may be an outlier. Can we exclude that point? Q = 0.67 If we compare our Q to the table, in order to exclude 9.1, our Q would have to be greater than 0.941. Since it is not, that data point must be included.

138. In forensics, usually working with a small sample, that is assumed to represent the entire population. This makes it difficult to compare the mean and the SD for our small sample to the mean and SD for the large sample. Example: Small sample measurements are 9.1, 12.3, 12.4 – the mean is 11.3. However, in this case the median – 12.3 might be more useful since two measurements are closers to the median. With smaller samples, sometimes the median is more useful than the mean.

139. Forensic Evidence typically relies on theoretical probabilities, which assume that all possible outcomes are equally likely and rely on simple mathematical expressions. Experimental probabilities are when all possible outcomes are not as likely, for example a die or deck of cards has been tampered with.

140. Definitions to Know: Outcome: Possible results from experiment Event: One particular outcome, often from several choices.

141. For example: the probability of rolling a 4 on a die would be 1/6: There is 1 “four” out of 6 possible outcomes.

142. What is the probability of drawing the King of Hearts out a deck of cards? What is the probability of drawing a King out of a deck of cards? What is the probability of drawing a red card out of a deck of cards?

143. In forensics, we are often trying to tie two independent events together. To calculate: Multiply the probabilities of each individual event together.

144. When juries must decide between two different competing hypotheses: they use a likelihood ratio (LR). When LR is large: the prosecution has a stronger case, and the defendant is likely to be convicted. When LR is small: Defense has a stronger case, the defendant is likely to be acquitted.

145. The LR can be affected by each piece of new evidence brought into the trial, so the LR is constantly being reevaluated. If a piece of evidence helps the prosecution: the LR gets multiplied by a number larger than 1, to increase the LR. When a piece of evidence helps the defense: the LR gets multiplied by a number less than 1, to decrease the LR.

146. The likelihood ratio is often used to give juries an indication of the evidential value. Often DNA evidence is presented with the likelihood ratio that the DNA came from the suspect and not a random person in a population.

147. The nature of science dictates that we impartially evaluate data and do not take sides to support one hypothesis or another. In forensics, this is even more important due to the ramifications of the results of evidence testing and analysis. To avoid as much bias as possible, forensic scientists comply with stringent protocols, procedure and scrutiny to ensure their results are reproducible, reliable and impartial.

148. The concept of falsifiability – the idea that a hypothesis can be disproved after reproducible results and observations. Forensic scientists are trained to not only look for data to support the hypothesis but more importantly pay close attention to any data that may contradict the hypothesis.

149. How do we define ethics? Ethics involves questions that deal with our understanding of right and wrong and which pathway to follow. Ethics in forensic science helps keep the judicial system fair, accurate and helps guide how science can effectively operate within the context of the legal system.

150. Ethical and moral codes have been set up for forensic labs and experts by several organizations. The American Academy of Forensic Science (AAFS) has established guidelines to help all scientists adhere to highest standards in the field.

152. An established code of ethics help balance the difficult task that forensic scientists are faced with: upholding good scientific practice and principles while immersed in a legal setting. Most crime labs are divisions within the law enforcement agency of the area. They work closely with police, district attorneys and appear in court for prosecution.

153. While they are routinely working with law enforcement, they have an obligation to remain impartial to one side or the other. Further complicating matters, the funding for most crime labs is within funding for law enforcement.

154. The defense is allowed to have access to the results and reports that were conducted by the crime lab. However, they do not have the right to retest evidence under the Federal Rules of Evidence. While the defense is allowed to ask for the results and report – it is usually only used for final reports. Typically, the methods, lab notebooks, records or other notes taken are not given to the defense In addition, technically crime labs do not have the obligation to preserve samples to use for later retesting or even preserve records.

155. Recent Developments: The report “Strengthening Forensic Science in the United States: A Path Forward” was published in 2009. It concludes that forensic science protocols and methodology across the country need to be brought up to a higher, more uniform standard. Many groups have been working to begin raising the scientific standards, implement ethical codes of conduct and changing legal and laboratory best practices.