Crime Scene Investigation Introduction to Physical Evidence Types

Crime Scene Investigation Introduction to Physical Evidence

Types of Evidence l. Direct l. Circumstantial l. Testimonial l. Physical

Value of Physical Evidence Physical evidence can be defined as physical objects associated with a crime or tort.

Value of Physical Evidence Physical evidence collected at the scene might require analysis and interpretation to be of value.

Value of Physical Evidence In order to be of value, it is critical that the physical evidence be: Recognized as potential evidence l Collected in an appropriate manner l Preserved properly for transmittal to the laboratory Failure to do any of the above might compromise or destroy the evidence. l

Value of Physical Evidence 1. It can be used to RECONSTRUCT a crime scene. Reconstruction of the crime scene is one of the major purposes for the collection of physical evidence.

Value of Physical Evidence 2. It can be used to determine whether or not a crime occurred.

Value of Physical Evidence 3. It can link one individual with another or an individual with a place. Locard’s Exchange Principal Suspect Victim Scene

Value of Physical Evidence 4. It can provide investigative leads to the investigator. The initial examination of physical evidence from the crime scene may provide sufficient leads, such as the identity of the perpetrator.

Value of Physical Evidence 5. It can provide information to a jury to assist them in determining a verdict. The analysis of physical evidence can provide proof of the guilt or innocence of an accused person.

Value of Physical Evidence 6. It can link different cases together. Physical evidence is often the strongest link between a series of crimes and the perpetrator.

Advantages of Physical Evidence Provides a tangible object for the jury to see.

Advantages of Physical Evidence Can be carried into the jury room to aid in deliberation.

Advantages of Physical Evidence The defendant cannot distort the physical evidence.

Advantages of Physical Evidence Some cases cannot be solved without physical evidence.

Advantages of Physical Evidence Physical evidence is not subject to memory loss.

Advantages of Physical Evidence Defendant can have the evidence tested by an independent expert.

Major Categories of Physical Evidence LATENT FINGERPRINTS & IMPRESSION EVIDENCE

Major Categories of Physical Evidence L ATENT FINGERPRINTS & IMPRESSION EVIDENCE l Fingerprints l Footprints l Tire Impressions l Shoe Impressions

Major Categories of Physical Evidence FIREARMS &TOOLMARKS

Major Categories of Physical Evidence l Firearms l FIREARMS & TOOLMARKS l l l l Examined for operability Comparison of bullets Comparison of cartridge cases Comparison of shotshell cases Toolmarks Serial numbers Analysis of clothing for GSR Patterns & Distance

Major Categories of Physical Evidence FORENSIC BIOLOGY

Major Categories of Physical Evidence FORENSIC BIOLOGY Examine physical evidence for presence of biological material l Conduct DNA analysis l Compare DNA from unsolved cases to a computerized database of DNA profiles from convicted offenders, arrestees, and other crime scene samples to provide possible investigative leads to law enforcement officers l

Major Categories of Physical Evidence TRACE EVIDENCE

Major Categories of Physical Evidence Fire Debris l Explosives l Paint l Hair & Fiber l Glass l Gunshot Residue l Fabric Separations l General Chemicals l TRACE EVIDENCE

Major Categories of Physical Evidence QUESTIONED DOCUMENTS

Major Categories of Physical Evidence QUESTIONED DOCUMENTS l l Examine questioned and known handwritten or hand printed documents to identify the author Examine mechanically produced documents to identify the source of the documents Examine documents for erasures, alterations, obliterations, indented writing, secret or disappearing ink and to recover original texts Examine charred and water soaked documents to recover the original text and perform physical matches of torn or cut paper products

Major Categories of Physical Evidence FORENSIC TOXICOLOGY

Major Categories of Physical Evidence FORENSIC TOXICOLOGY l Medical Examiner Cases l Driving Under the Influence l Police Cases

Major Categories of Physical Evidence CONTROLLED SUBSTANCES

Major Categories of Physical Evidence CONTROLLED SUBSTANCES l Examiners in the Controlled Substances section test materials for the presence of controlled substances or marijuana. l Illegal drugs may be presented in powders, solid material, liquids, or LSD blotter paper, as well as in plants and mushrooms.

Major Categories of Physical Evidence BLOODSTAIN PATTERN ANALYSIS

Major Categories of Physical Evidence BLOODSTAIN PATTERN ANALYSIS Blood, as it is deposited, creates a pattern and provides a basis for study. A reconstruction can be utilized which demonstrates the course of events and possibly a sequence of events.

Major Categories of Physical Evidence FORENSIC IMAGING

Major Categories of Physical Evidence FORENSIC IMAGING l Image Enhancement l Video Enhancement l Audio Enhancement l Forensic Photography l Photo Processing