Ch. 12: The Forensics Laboratory

I. Forensics Lab A.Must be accredited and are monitored to keep this accreditation B.Quality assurance program 1. Necessary to meet accreditation requirements 2. Includes education of staff, peer review of results, evidence handling, lab security, proficiency tests, etc. (Proficiency tests = simulated forensic cases produced internally or by outside testing agency) C. Director of lab = criminalist

I. Forensics Lab (continued) D. Association with a law enforcement agency helps with the free EXCHANGE of info and access to CS and physical evidence

II. Criminalist A. Difference between forensics and criminalistics 1. forensics = more general --Can apply to any # of scientific disciplines (ex. anthropology and odontology) 2. Criminalist = a scientist who applies the principles of primarily biology, physics, and chemistry to evidence analysis AND is also trained in crime scene investigation and reconstruction

B. Role of criminalist 1. Provide investigative leads....How? a. Through scientific evaluation of physical evidence and a crime scene reconstruction b. Report results and conclusions of the scientific evaluations

B. Role of a criminalist (continued) 2.To act as an... a. Investigator—asking questions, communicating with police b. Educator—educate individuals at all levels of a case (i.e. law enforcement officers, CSI, attorneys, judges, etc.)—expert testimony c. Student—must stay current and continue to learn because of advancing technology and trends

III. Classifying and using physical evidence in a lab A. Reconstruction Evidence 1. Provides info about events preceding, occurring during, and after a crime 2. Three commonly used tools to help locate reconstruction evidence a. Luminol = chemical that reacts with minutes quantities of blood b. Alternate light source = detects body fluid stains, fibers, other compounds that fluoresce under various wavelengths of light c. Blood stain analysis

Luminol nimations/images/blood%2 0spatters.swf Blood stain pattern

III.Classifying and using physical evidence in a lab (continued) B. Associative Evidence 1. Is evidence that can be used to associate or dissociate a suspect to a crime 2. Further subdivided into... a.Individual or identification evidence = evidence is linked to a particular source Ex. fingerprints, DNA profiles, some impressions, and fracture matches b. Class characteristic evidence = evidence is associated with a group and not considered unique --Conclusions regarding class characteristic evidence are limited