1. Types of Evidence Chapter 3 Notes bsapp.com

2. I CAN Skills for the Physical Evidence Unit I Can review the common types of physical evidence at crime scenes. I Can review the common types of physical evidence at crime scenes. I Can explain the difference between the identification and comparison of physical evidence. I Can explain the difference between the identification and comparison of physical evidence. I can define and contrast individual and class characteristic of physical evidence. I can define and contrast individual and class characteristic of physical evidence. I can explain the value of class evidence as it relates to a crime case. I can explain the value of class evidence as it relates to a crime case. I can list and explain the function of national databases available to forensic scientists. I can list and explain the function of national databases available to forensic scientists.

3. Edmond Locard (1877-1966) French investigator Background in medicine and law 1910-started a police laboratory Founded Institute of Criminalistics at the University of Lyons Contributed to fingerprints (poroscopy)

4. Locard’s Exchange Principle 1.Principle of cross-transfer 2.Whenever two objects come into contact there is evidence of that contact through cross-transfer… 3.Microscopic 4.Macroscopic Every contact leaves a trace!

5. PHYSICAL EVIDENCE CAN: 1. Prove that a crime has been committed or establish key elements of a crime. Example Rape = victim has torn clothing, bruises, broken arm = non- consensual 2. Link a suspect with the victim or crime scene Example : Burglary = suspect has broken glass shards in his pants cuff that are consistent with glass shards at scene 3. Establish the identity of persons associated with a crime Example : Latent fingerprints identified through AFIS. DNA identified through CODIS.

6. PHYSICAL EVIDENCE CAN: 4. 4.Exonerate the innocent. Example : Rape = DNA preserved was compared against man convicted of the crime = no match. 5. 5.Corroborate the victim’s story. Example: Officer involved shootings during arresting a suspect. 6. 6.Contradict information provided to investigators. Example : Discredit a witness; elicit a confession 7. Be more reliable than eyewitness testimony. “[Physical Evidence] does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. It cannot be wrong; it cannot perjure itself; it cannot be wholly absent. Only in it’s interpretation can there be error. Only human failure to find, study, and understand it can diminish its value.” Paul Kirk, Crime Investigation, 1953

7. PHYSICAL EVIDENCE CAN: 8. 8. Be the cornerstone of a case. Police/prosecutors are expected to obtain physical evidence and rarely rely on a confession alone. 9. And IS expected by a jury/the public. TV, books, media focus on physical evidence and the miracles performed (reality vs. fantasy) 10. Support or refute a theory. The absence of forced entry in a burglary case…

8. Class and Individual Characteristics of Evidence Class characteristics : Evidence can only be associated with a group and not a unique source Individual characteristics: Evidence can be attributed to a unique source with a high degree of certainty (or even to the exclusion of all others)

9. Examples of Class Characteristics 1. 1.Shoes (Tennis shoe; Nike) 2. 2.Paint (Cherry red car paint) 3. 3.Fibers ( polyester fiber, braided weave) 4. 4.Fingerprints (loops, whorls, arches) 5. 5.Toolmarks (knife scratch, screwdriver marks) 6. 6.Firearms (.40 caliber slug) 7. 7.Arson (accelerants) 8. 8.DNA (male…remember the sex genes; XY) or the female XX genes in a genotype of the blood.

10. Individual Characteristics of Evidence at a Crime Scene 1. 1.Shoes (Nike Lunar Vapor 8 Tour Men's Tennis Shoe, size 7) 2. 2.Paint (physical match with a identified car) 3. 3.Fibers (physical match, unique “trait” of a particular garmet) 4. 4.Fingerprints (ridge detail enough for database comparison) 5. 5.Toolmarks (unique stria markings) 6. 6.Firearms (stria matching a test fired bullet, firing pin markings) 7. 7.DNA (profile that matches the suspect identically.)

11. Value of Class Physical Evidence The value of class evidence lies in its ability to corroborate events in a manner that is nearly free of human error and bias. Class evidence is not as specific as individual, but can produce results that exclude a suspect. The value of class evidence lies in its ability to corroborate events in a manner that is nearly free of human error and bias. Class evidence is not as specific as individual, but can produce results that exclude a suspect. As the number of different objects links an individual to a crime scene. As the number of different objects links an individual to a crime scene. A person may be excluded or exonerated from suspicion if physics evidence collected at a crime scene is found to be different from the standard samples taken from the individual. DNA A person may be excluded or exonerated from suspicion if physics evidence collected at a crime scene is found to be different from the standard samples taken from the individual. DNA

12. Common Types of Physical Evidence Biological Human / animal origins Human / animal origins –Blood –Saliva –Semen –DNA hair profile. –Physiological fluids –Fingerprints –Hair –Tissues –Bodies

13. Type of Analysis of Blood, Semen, Saliva, Organs, & other Physiological Fluids Origin – Comparison to known suspects or witnesses, victims. Origin – Comparison to known suspects or witnesses, victims. DNA- Lab analysis to prove who was there and who was not. DNA- Lab analysis to prove who was there and who was not. Condition- samples must be in good enough condition to be analyzed. Watch for contamination with external chemicals / materials. Condition- samples must be in good enough condition to be analyzed. Watch for contamination with external chemicals / materials. bsapp.com

14. Examples of Physical Evidence being Individual and Proof 1. 1.Pathology wound matches murder weapon… 2. 2.Glass fragments found in burglar’s coat pocket… 3. 3.Burglar’s tools… 4. 4.Poison found in suspect’s home with rare component…

15. Fingerprints Mainstay of Forensics Mainstay of Forensics Who is on file? Who is on file? bsapp.com

16. Hair What type? What type? How removed? How removed? Match to a person Match to a person DNA DNA bsapp.com

17. Impression Crime Scene Evidence Tire Markings – types and sizes of tires, weights Tire Markings – types and sizes of tires, weights Shoe prints - tread, depth, weight, forces Shoe prints - tread, depth, weight, forces Depressions in soft soils- Remnants of actions and activities of numerous people or animals. Depressions in soft soils- Remnants of actions and activities of numerous people or animals. All types of tracks- machines, animals, humans. All types of tracks- machines, animals, humans. Material Impressions Material Impressions –Fabric- gloves, clothing, packs and cases. –Tool marks- hand tools, machine parts, bullet riffling. –Bite marks- human, dog, lions and tigers and bears! –Impact impressions – car lisence plates, bumper shapes. –Soils, mud, waste residue.

18. Impressions bsapp.com

20. Tool Marks Match tool to scares Match tool to scares bsapp.com

21. Soils, Minerals, Wood, and Other Vegetative Matter. Location Location Link suspect Link suspect Trace Evidence Trace Evidence bsapp.com

22. MANUFACTURED ITEMS These are man made items that are very commonly found at the scene of a crime. These are man made items that are very commonly found at the scene of a crime. –Weapons of all kinds: Firearms, ammo, knives, swords, machetes, chainsaws, ropes, explosives, bombs or components like blasting caps. –Polymers, plastic bags, paint, glass, fibers, petroleum products, vehicle headlights. –Drugs, chemicals, –Documents or computer programs.

23. Firearms and Ammunition Circumstances of discharge Circumstances of discharge Link to suspect Link to suspect Link to weapon Link to weapon Link to victim Link to victim bsapp.com

24. Powder Residue Evidence of shooting Evidence of shooting Circumstances of shooting Circumstances of shooting Type of weapon Type of weapon bsapp.com

25. Drugs Type of Drug? Type of Drug? Strength? Strength? Origin? Origin? Legal? Legal? bsapp.com

26. Explosives & Propellants Link to suspect or victim by person, place or thing. Link to suspect or victim by person, place or thing. Origin; military, civilian? Origin; military, civilian? bsapp.com

27. Fibers Link suspect to a location or victim by direct comparison Link suspect to a location or victim by direct comparison Origin? Type? Origin? Type? bsapp.com

28. Glass How broken? How broken? Link a suspect to a crime scene Link a suspect to a crime scene Fingerprints Fingerprints Blood; type. Blood; type. bsapp.com

29. Paint Origin Origin Match Match

30. Documents Hand written Hand written Type or Printed Type or Printed Authenticity? Authenticity? bsapp.com

31. Types of Analysis Comparison Comparison Visual Visual Microscopic Microscopic Chemical Chemical bsapp.com

32. Comparison Most types of evidence require a control with which to be compared bsapp.com http://www.fbi.gov/about-us/cjis/fingerprints_biometrics/iafis/iafis

33. IDENTIFICATION Identification has as its purpose the determination of the physical or chemical identity of a substance with near certainty in accuracy. Identification has as its purpose the determination of the physical or chemical identity of a substance with near certainty in accuracy. –Identify the substance and rule out any closely related substance. Ex. Drugs. Make sure it is cocaine and not PCP. –Standards within databases are compared by computer analysis to help speed things up.  http://webbook.nist.gov/chemistry/ http://webbook.nist.gov/chemistry/  http://www.fbi.gov/about- us/cjis/fingerprints_biometrics/iafis/iafis

34. Visual Analysis Evidence utilized through unaided observation bsapp.com

35. Microscopic Analysis Evidence observed with the use of some type of microscope bsapp.com

36. Chemical Analysis Evidence subjected to any type of chemical procedure bsapp.com