Forensic Science: An Introduction

Forensic Science In its broadest definition it is the application of science to law In its broadest definition it is the application of science to law Applies to the knowledge and technology of science for the definition and enforcement of such laws Applies to the knowledge and technology of science for the definition and enforcement of such laws Definition: the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system Definition: the application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system

Sciences involved Chemistry Chemistry Biology Biology Physics Physics Geology Geology Forensic pathology Forensic pathology Forensic psychology Forensic psychology Forensic Odontology Forensic Odontology

History of Forensic Science Sir Arthur Conan Doyle: fictional character Sherlock Holmes had a great influence on popularizing the study of crime scenes Sir Arthur Conan Doyle: fictional character Sherlock Holmes had a great influence on popularizing the study of crime scenes Holmes was the first to apply the principles of serology (blood typing and analysis), fingerprinting, firearm identification and document examination Holmes was the first to apply the principles of serology (blood typing and analysis), fingerprinting, firearm identification and document examination First book in 1887 “A Study in Scarlet” First book in 1887 “A Study in Scarlet”

Important People Mathieu Orfila ( ) father of forensic toxicology; detection of poisons and their effects Mathieu Orfila ( ) father of forensic toxicology; detection of poisons and their effects Alphonse Bertillon ( ) scientific system for personal identification; taking body measurements as a means of distinguishing people; father of criminal identification Alphonse Bertillon ( ) scientific system for personal identification; taking body measurements as a means of distinguishing people; father of criminal identification

Important People Francis Galton ( ) study of fingerprints and developed method for classifying them for filing Francis Galton ( ) study of fingerprints and developed method for classifying them for filing Karl Landsteiner in 1901 discovered ABO blood types Karl Landsteiner in 1901 discovered ABO blood types Leone Lattes ( ) devised a procedure for determining blood group of a dried bloodstain Leone Lattes ( ) devised a procedure for determining blood group of a dried bloodstain

Important People Calvin Goddard ( ) comparison microscope to identify bullets Calvin Goddard ( ) comparison microscope to identify bullets Albert Osborn ( ) document examination Albert Osborn ( ) document examination Walter McCrone ( ) known as the world’s preeminent microscopist; instructor, and author Walter McCrone ( ) known as the world’s preeminent microscopist; instructor, and author

Important People Hans Gross ( ) Austrian judge who described the application of scientific disciplines to the field of criminal investigation. Hans Gross ( ) Austrian judge who described the application of scientific disciplines to the field of criminal investigation. Zoology, botany, anthropology, fingerprinting Zoology, botany, anthropology, fingerprinting Edmond Locard ( ) founder and director of the Institute of Criminalistics at the University of Lyons; workable crime lab Edmond Locard ( ) founder and director of the Institute of Criminalistics at the University of Lyons; workable crime lab

Important People Edmond Locard: Edmond Locard: Locard’s Exchange Theory: the exchange of materials between two objects that occurs whenever two objects come into contact with one anther Locard’s Exchange Theory: the exchange of materials between two objects that occurs whenever two objects come into contact with one anther Locard believed every criminal can be connected to a crime by dust particles carried from the crime scene Locard believed every criminal can be connected to a crime by dust particles carried from the crime scene

Major influencers #1 reason for increased need of trained scientists is the increase in drug sale and usage in the world #1 reason for increased need of trained scientists is the increase in drug sale and usage in the world All illicit drug seizures must be sent to a forensic lab for confirmatory chemical analysis before the case can go to court All illicit drug seizures must be sent to a forensic lab for confirmatory chemical analysis before the case can go to court

4 Federal Crime Labs FBI: largest crime lab FBI: largest crime lab DEA Drug Enforcement Agency: analysis of drugs seized in violation of federal laws for production, sale and transportation of drugs DEA Drug Enforcement Agency: analysis of drugs seized in violation of federal laws for production, sale and transportation of drugs ATFE Bureau of Alcohol Tobacco Firearms and Explosives: responsible for analyzing alcoholic beverages and documents relating to tax law enforcement and for examining weapons, explosive devices, and related evidence ATFE Bureau of Alcohol Tobacco Firearms and Explosives: responsible for analyzing alcoholic beverages and documents relating to tax law enforcement and for examining weapons, explosive devices, and related evidence U.S. Postal Inspection Services: maintains lab concerned w/criminal investigations relating to the postal service U.S. Postal Inspection Services: maintains lab concerned w/criminal investigations relating to the postal service

Crime Lab Services Basic Services Photography Photography Physical Science Physical Science Biology/DNA Biology/DNA Firearms Firearms Document Examination Document Examination Optional Services Toxicology Toxicology Latent Fingerprint Latent Fingerprint Polygraphy Polygraphy Voice Analysis Voice Analysis Forensic Psychiatry Forensic Psychiatry Forensic Odontology Forensic Odontology Forensic Engineering Forensic Engineering Forensic Computer and Digital Analysis Forensic Computer and Digital Analysis

What Forensic Scientists Do Analyze physical evidence Analyze physical evidence Use scientific methods Use scientific methods Determine admissibility of evidence Determine admissibility of evidence Frye v US (1923) – general acceptance Frye v US (1923) – general acceptance Judge scientific evidence Judge scientific evidence Daubert case (1993) – trial judge is gatekeeper Daubert case (1993) – trial judge is gatekeeper Provide expert testimony Provide expert testimony Furnish training Furnish training

Physical Evidence Anything physical objects that can link a crime to its victims or to suspects. Anything physical objects that can link a crime to its victims or to suspects. Has to be collected from crime scene Has to be collected from crime scene Must be relevant to the crime Must be relevant to the crime Requires the collector to understand what the capabilities and limitations of the crime lab are Requires the collector to understand what the capabilities and limitations of the crime lab are

Physical Evidence Crime labs do not solve crimes, only add evidence to help police investigation link the suspect to the crime. Crime labs do not solve crimes, only add evidence to help police investigation link the suspect to the crime. The forensic scientists must know how to collect and preserve evidence found at the crime scene The forensic scientists must know how to collect and preserve evidence found at the crime scene

Arriving at the Crime Scene Secure and isolate the crime scene Secure and isolate the crime scene Determine boundaries of crime scene and priorities for evidence collection Determine boundaries of crime scene and priorities for evidence collection Rough sketch Rough sketch Finished sketch Finished sketch Photograph Photograph Videotaping Videotaping Notes Notes

Collecting Evidence Conduct a systematic search for evidence; be unabiased and thorough. Conduct a systematic search for evidence; be unabiased and thorough. Field technicians Field technicians What to look for depends on the crime and what specific locations of the crime scene would most likely be affected What to look for depends on the crime and what specific locations of the crime scene would most likely be affected Microscopic or massive objects Microscopic or massive objects Collect carriers of possible evidence Collect carriers of possible evidence Vacuum or sweeping collected Vacuum or sweeping collected

Packaging of Evidence Prevent any changes from occurring (contamination, breakage, evaporation, bending, loss) Prevent any changes from occurring (contamination, breakage, evaporation, bending, loss) Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possible Process trace evidence from original object (shirt, shoe) rather than isolating and packaging if possible Package evidence separately Package evidence separately

Tools for Collecting Evidence Forceps Forceps Evidence envelopes and pill bottles Evidence envelopes and pill bottles Swabs Swabs Special concerns (mold, evaporation) Special concerns (mold, evaporation) Various light sources Various light sources Latent fingerprints Latent fingerprints Mobile crime labs or better yet crime scene search vehicle Mobile crime labs or better yet crime scene search vehicle

Chain of custody Continuity of possession; every person who touched it must be accounted for Continuity of possession; every person who touched it must be accounted for Standards for collecting, labeling, and submitting evidence forms are necessary for court Standards for collecting, labeling, and submitting evidence forms are necessary for court Labels include collectors initials, location of evidence, date of collection. Identification numbers must also be used Labels include collectors initials, location of evidence, date of collection. Identification numbers must also be used

Submission of Evidence Standard/reference samples Standard/reference samples Substance controls Substance controls Evidence submission form will detail the evidence collect and particular type of examination/analysis requested. Evidence submission form will detail the evidence collect and particular type of examination/analysis requested. Lab tech not bound by requests Lab tech not bound by requests

Common Types of Evidence Common Types of Evidence Common Types of Evidence Blood, semen, and saliva Blood, semen, and saliva Documents Documents Drugs Drugs Fibers Fibers Fingerprints Fingerprints Firearms and ammunition Firearms and ammunition Glass Glass Hair Hair Impressions Impressions Organs and physiological fluids Organs and physiological fluids Paint Paint Petroleum products Petroleum products Plastic bags Plastic bags Plastic, rubber, and other polymers Plastic, rubber, and other polymers Powder residues Powder residues Serial numbers Serial numbers Soil and minerals Soil and minerals Tool marks Tool marks Vehicle lights Vehicle lights Wood and other vegetative matter Wood and other vegetative matter

Examination of Physical Evidence Identification Identification Determining the identity of a substance with a near absolute certainty while ruling out other substances Determining the identity of a substance with a near absolute certainty while ruling out other substances Comparison Comparison Comparing the evidence to one or more selected references and drawing a conclusion about its origins. Comparing the evidence to one or more selected references and drawing a conclusion about its origins. Individual characteristics –properties of evidence that can be attributed to a common source with extremely high certainty. (eg. fingerprints, DNA, bullets) Individual characteristics –properties of evidence that can be attributed to a common source with extremely high certainty. (eg. fingerprints, DNA, bullets) Class characteristics – properties of evidence that can be associated with a group and never with a single source. ( eg. Blood type, tire marks) Class characteristics – properties of evidence that can be associated with a group and never with a single source. ( eg. Blood type, tire marks)

Significance of Physical Evidence Assessing the values of evidence Assessing the values of evidence Class characteristics of evidence is valuable in corroborating events. Class characteristics of evidence is valuable in corroborating events. Multiple class evidence can lead to a high level of certainty of origin Multiple class evidence can lead to a high level of certainty of origin Cautions and limitations of evidence Cautions and limitations of evidence A person can be exonerated or excluded from suspicion if evidence collected from the crime scene is different from the reference samples collected from the person. A person can be exonerated or excluded from suspicion if evidence collected from the crime scene is different from the reference samples collected from the person.

Forensic Databases One-on-one comparison requires a suspect One-on-one comparison requires a suspect Computerized databases help link evidence to people Computerized databases help link evidence to people Fingerprint databases – IAFIS Fingerprint databases – IAFIS DNA database – CoDIS DNA database – CoDIS Ballistics database – IBIS Ballistics database – IBIS Automative Paint database – PDQ Automative Paint database – PDQ Shoeprint database - SICaR Shoeprint database - SICaR

Crime-Scene Reconstruction The method used to support a likely sequence of events at a crime scene by observing and evaluating physical evidence and statements made by those involved with the incident The method used to support a likely sequence of events at a crime scene by observing and evaluating physical evidence and statements made by those involved with the incident Combined efforts of MEs, CSI, and law enforcement personnel Combined efforts of MEs, CSI, and law enforcement personnel Examples: was body moved, bullet trajectory, blood splatter Examples: was body moved, bullet trajectory, blood splatter