Psychology of Homicide Unit III Lecture Criminalistics

Criminalistics or Forensics Definition of Terms Forensic science is the application of science to the criminal and civil laws that are enforced by police agencies in a criminal justice system. In this class we will focus on criminal laws.

Edmond Locard Locard’s Exchange Principle One of the most important contributors to criminalistics is Edmond Locard (1877-1966) whose main education was in law and medicine. Locard believed that when a person comes in contact with and object or person, a cross- transfer of materials occur, this is called “Locard’s exchange principle” and is the foundation of study of forensic science.

Expert Witness An individual whom the court determines to possess knowledge relevant to the trial that is not expected by the average layperson.

Forensic Psychiatry Is a specialized area in relationship between human behavior and legal proceedings is examined. For criminal cases forensic psychiatrist evaluate behavioral disorders to determine competency to stand trial, also examine behavioral patterns of criminals as an aid in developing a suspect’s behavioral profile.

Crime Laboratory Major Units Biology Unit

Biology unit-DNA, dried blood, body fluids, hair, fibers and botanical materials (wood and plants).

Firearms, discharged bullets, cartridge cases, shotgun shells, and ammunition. Also examination of garments and target to determine range and angle of shot. Examine stippling and gas expansion. Firearms Unit

Document Examination Unit Handwriting, typewriting, paper, ink, depressions, obliterations, and erasures, burned or charred documents. Document Examination Unit

Basic and digital imaging, infrared, ultraviolet and x- ray photography. Also prepared photographic exhibits for courtroom presentations. Photography Unit

Examines body fluids and organs to determine the presence or absence of drugs and poisons. Many times works under the direction of the medical examiner or coroner’s office. Toxicology Unit

AFIS-Latent Fingerprint Unit Utilizes AFIS to examine and processes evidence for latent fingerprints. Uses scientific techniques in order to produce quality fingerprint impressions. AFIS-Latent Fingerprint Unit

This unit dispatches specially trained technicians to secure, collect and preserve physical evidence. Specific steps to process a variety of homicide scenes with the first priority safety, then rendering first aid to survivors and last to process the scene. Crime Scene Unit

The Balance Test for Evidence The 50% plus a feather test. A test used to determine evidence that may be prejudicial or inflammatory to the jury. The evidence must be more probative than prejudicial. The Balance Test for Evidence

Admissibility of Evidence Frye v. United States (1923)-this standard states the court must decide whether the questioned procedure, technique, or principle is “generally accepted” by a meaningful segment of the relevant scientific community. (Some court do not use the Frye Test, but instead use the Federal Rules of Evidence, this would include the federal courts and some state court systems). Admissibility of Evidence

Daubert v. Merrell Dow Pharmaceuticals, Inc Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) stated the Frye Test is not an absolute. FRE-if scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or educations, may testify thereto in the form of an opinion or otherwise, if; (1) the testimony is based on sufficient facts or data (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied to the principles and methods reliability to the fact of the case.

The gatekeeper of the evidence is the trial judge, not only scientific evidence, but to all expert testimony. The Judge

The crime scene-safety line, evidence line, one way in and one way out The crime scene-safety line, evidence line, one way in and one way out. No media allowed and admittance only on a need basis. Do not walk on walkway. Record everyone in and out with a log. Identify and mark all evidence. Create sketch with accurate measurements. Bag and tag all evidence in appropriate containers. The Crime Scene Basics

Physical evidence-tangible items Physical evidence-tangible items. Wet biological items will need to dry before bagging. Drugs Toxicology Crime scene investigation Hair, fibers and paint Arson investigation Explosives Fingerprints Firearms Fingerprints-arch, loop and whorl Physical Evidence

Thank you! Questions?