Intro to Forensic Science
and
Crime Laboratories
2014-2015
Scientific Method
• Science derives it’s integrity from adherence to
guidelines and the scientific method
• Careful and systematic (orderly) collection, organization, and
analysis of information/evidence
• The underlying principles provide a safety net to
ensure that the outcome of an investigation is not
tainted by human emotion or compromised by
distorting, belittling, or ignoring contrary evidence
How To Be a Good Observer
• Pay attention to all the details of your
surroundings
• Place personal opinions and beliefs aside
• Rely on direct experience and knowledge
• Don’t jump to conclusions
• Write down and photograph as much
information as possible
• Memories are faulty
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
Specialty Units With Full Service
Crime Laboratories
• Biology Unit (Staffed w/ Biologists and Biochemists)
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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
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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