Intro to Forensic Science
and
Crime Laboratories
2014-2015
What is Forensic Science?
• Forensic Science is the study and application
of science to matters of the law.
• The term CRIMINILISTICS can be used
synonymously with FORENSIC SCIENCE
– Interchangeable (same meaning)
3 Major Avenues Available to Police
Investigators in Solving a Crime
• Confessions
• Some suspects may be coerced into confessions for fear of longer
sentences even though they are innocent
• Eyewitness Accounts by Victims or Witnesses
• Eyewitness accounts vary considerably from person to person
• Eyewitness accounts are unreliable and have led to the
imprisonment of many wrongfully convicted suspects
» INNOCENCE PROJECT – Project with aim to free wrongfully convicted
• 87% of all wrongful convictions were a result of flawed
eyewitness testimony
• Evaluation of Physical Evidence Retrieved From the Crime
Scene
• Only physical evidence is free of inherent error or bias
• Relies on science
Functions of a Forensic Scientist
• Find, examine, and evaluate evidence at a crime scene
• Observational skills are key!
• Must observe whole crime scene
– Avoid tunnel vision
– Collect all evidence and don’t jump to
conclusions
• Use analytical skills to examine evidence and draw conclusions
– ANALYTICAL SKILLS = the ability to identify a problem, isolate its
component parts, organize information for decision making, and
evaluate information to draw conclusions
– Using DEDUCTIVE REASONING- using logic while studying all known
facts to come to a conclusion
• Act as expert witnesses for prosecution or defense attorneys
Crime Labs
• Nearly Four hundred public crime labs in US
– More than 3 times that of 1966
• Growth due to…
– Supreme court cases in 1960’s placed more
emphasis on police securing scientifically
evaluated evidence
– Increased Crime Rates
– Increased Drug Abuse- All evidence from illicit
seizures must be sent to crime Lab for chemical
analysis
Crime Lab Challenges
• Not enough labs to keep up with needs
• DNA Profiling (Fingerprinting)- Major Reason for increased
Demand
– Technology did not exist prior to early 1990’s
– Traces of Blood, Saliva, Hair, Epithelial Tissue (Skin), and Semen
backlog crime labs
– Over 57,000 unanalyzed case samples
– Untested convicted offender samples over 500,000
– Tested samples go to CODIS (National DNA Databank)
• Combined DNA Index System
– Some states have own Database
– CA over 1 million in state database
» 3rd Largest in world
» Starting in 2008 all people arrested and suspected of felony charges were profiled
Types of Crime Laboratories
• Federal Crime Laboratories
– FBI Crime Lab (Quanitico Virginia), largest in WORLD
– DEA, and Bureau of Alcohol, Tobacco, Firearms, and
Explosives located within
– Will offer assistance and expertise to state and local
agencies
• State and Local Crime Laboratories
– State Labs, Most States Have State Lab
• Some have statewide system with regional satellite labs
– County and Municipal Crime Labs
• Some Counties have
• Larger Cities, NY city is largest.
• Many smaller cities do not have due to cost
Specialty Units With Full Service
Crime Laboratories
• Biology Unit (Staffed w/ Biologists and Biochemists)
–
–
–
–
DNA Profiling
Blood Evidence and Other Bodily Fluids
Hair and Fiber Analysis
Plant Materials Such as wood and Plants
• Firearms Unit
– Ballistics (Bullet and Firearm Analysis)
– Gun Powder Residue
– Crime Scene Reconstruction (Distance from which weapons are
fired)
• Document Examination Unit
– Handwriting and Typewriter Analysis
– Ink and Paper Analysis
– Erasures/Depressions
Specialty Units With Full Service
Crime Laboratories (continued)
• Photography Unit
– Examines and records physical evidence through
photography
– Sometimes advance techniques used (infrared, X-Ray,
digital imaging ect…)
• Toxicology and Drug Analysis Unit
–
–
–
–
Examines Body Fluids and Organs
Detect Presence or absence of drugs and poisons
Evidence may be sent to separate 3rd party facility
Often maintain field instruments such as Intoxilyzer
• Fingerprint/Latent Fingerprint Unit
– Fingerprint Analysis
Specialty Units With Full Service
Crime Laboratories (continued)
• Polygraph Unit
– Lie Detector
– Investigator tool yet not forensic scientist tool
– Still kept in crime lab unit though
• Voiceprint Analysis Unit
– Use sound spectrograph that transforms speech in to visual display
called voiceprint
– Analyze recorded voice evidence (Tape recorder/phone calls ect…)
• Crime Scene Investigation Unit
– Collect and preserve physical evidence that is later analyzed at crime
lab
– Must maintain chain of custody and check evidence in to evidence
room
Other Forensic Science Services
• Forensic Psychiatry
– Used in criminal and civil proceedings
• Determine competence
• Evaluate behavioral disorders
• Forensic Odontology
– Id victims in unrecognizable state
– Bite mark analysis
• Forensic Engineering
– Failure analysis (buildings)
– Accident reconstruction
• Examine, photograph, and review of mechanical objects
• Forensic Computer and Digital Analysis
– Newest and fastest growing
– Identification, collection, preservation, and examination from
computers and other digital devices