Introduction to Crime Scene Investigation and Evidence Types

EVIDENCE

ANYTHING THAT IS LEGALLY SUBMITTED TO A COMPETENT TRIER OF FACT AS A MEANS OF ASCERTAINING THE TRUTH OF ANY ALLEGED MATTER UNDER INVESTIGATION.

TRIER OF FACT

THE "TRIER OF FACT" MAY BE EITHER: THE JUDGE, IN THE CASE OF A BENCH TRIAL, OR THE JURY, IN THE CASE OF A JURY TRIAL.

TESTIMONIAL EVIDENCE

GIVEN IN THE FORM OF STATEMENTS MADE UNDER OATH, USUALLY IN RESPONSE TO QUESTIONING.

REAL EVIDENCE

EVIDENCE THAT HAS OBJECTIVE EXISTENCE. IN OTHER WORDS, THIS TYPE OF EVIDENCE HAS SIZE, SHAPE, AND DIMENSION.

PHYSICAL EVIDENCE

ALSO KNOWN AS "REAL EVIDENCE".

DIRECT EVIDENCE

THIS TYPE OF EVIDENCE SUPPORTS A CONCLUSION OF FACT WITHOUT INFERENCE.

CIRCUMSTANTIAL EVIDENCE

THIS TYPE OF EVIDENCE REQUIRES INFERENCE TO CONNECT IT TO A CONCLUSION OF FACT.

ASSOCIATIVE EVIDENCE

EVIDENCE THAT CAN BE ATTRIBUTED TO, OR ASSOCIATED WITH, A SPECIFIC PERSON, PLACE, OR THING, THUS ESTABLISHING INFERRED CONNECTIVITY.

TRACE EVIDENCE

ANY EVIDENCE THAT IS SMALL (I.E., HAIRS, FIBERS, PAINT, GLASS, SOIL), WHICH WOULD REQUIRE MICROSCOPIC ANALYSIS TO IDENTIFY IT.

TRANSFER EVIDENCE

A TYPE OF EVIDENCE THAT IS PASSED FROM ONE ITEM TO ANOTHER, TYPICALLY BECAUSE OF CONTACT OR ACTION.

TRANSIENT EVIDENCE

PHYSICAL EVIDENCE PRESENT AT THE CRIME SCENE THAT IS EITHER FRAGILE OR AT GREAT RISK FOR LOSS, ALTERATION, OR DESTRUCTION IF NOT PROPERLY IDENTIFIED, DOCUMENTED, COLLECTED AND PRESERVED AS SOON AS POSSIBLE.

CLASSIFICATION OF PHYSICAL EVIDENCE

OCCURS WHEN AN ITEM OF EVIDENCE IS ASSIGNED TO A SPECIFIC CLASS WHERE IT BELONGS.

CLASS CHARACTERISTICS

THE CHEMICAL/PHYSICAL PROPERTIES OF THE GROUP.

INDIVIDUALIZATION OF PHYSICAL EVIDENCE

OCCURS WHEN AN ITEM OF EVIDENCE IS ASSIGNED TO A CLASS CONTAINING ONLY ONE MEMBER (I.E., ITSELF).

INDIVIDUAL CHARACTERISTICS

UNIQUE PROPERTIES THAT IDENTIFY AN ITEM OF EVIDENCE.

COURT ORDERS

SEARCH WARRANTS MAY BE REQUIRED TO SEARCH A CRIME SCENE AND/OR FOR THE COLLECTION OF EVIDENCE, SUCH AS BLOOD SAMPLES, HAIR SPECIMEN, TEETH IMPRESSIONS, ETC. FROM A SUSPECT.

Case Law

Dynamic legal principles that may require consultation with the prosecutor's office if there's doubt about what can be collected.

Fruit of the Poisonous Tree

Illegally collected evidence that can be deemed inadmissible in court.

Exigent Circumstances

Conditions under which evidence may be collected without a court order.

Chain of Custody

A process initiated and maintained to ensure the integrity of evidence and to prove that evidence submitted to court is the evidence collected at the scene.

Chain of Evidence

Also known as the chain of custody, it refers to the documentation of the handling of evidence.

Questioned Samples

Samples collected at the crime scene from an unknown or unidentified source and submitted to the laboratory for testing and identification.

Known Samples

Samples from an identified or known source provided to the crime laboratory for comparison to unknown or questioned samples.

Reference Samples

Another term for known samples used for comparison in forensic analysis.

Elimination Samples

Samples taken from individuals who have had legitimate access to a crime scene, used to exclude them from being suspects.

Blank Samples

Samples that do not contain evidence but are collected, packaged, and preserved using the same method as questioned samples.

Appropriate Packaging

General rule of thumb states that plastic bags are not allowed for certain types of evidence, such as blood items and volatile substances.

Contact Evidence

Physical evidence that can place a suspect in contact with the victim or the crime scene.

Identity Establishment

Physical evidence that can establish the identity of persons associated with the crime.

Exoneration

Physical evidence that can exonerate the innocent.

Corroboration

Physical evidence that can corroborate the victim's testimony.

Admissions or Confessions

Suspects confronted with physical evidence may make admissions or confessions.

Reliability of Evidence

Physical evidence may be more reliable than eyewitnesses to a crime.

Jury Expectations

Juries in criminal cases expect physical evidence to be presented.

Negative Evidence

Evidence that may provide useful information about the events that occurred at the scene.