Trauma and Crime Scene Technician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Locard's exchange principle

Every contact between a person and an object or another person results in transfer of material in both directions, which is the basis for associative trace evidence collection.

Transient evidence

Evidence that degrades or disappears with time or environmental change, such as odors, wet blood, or impressions in snow, and is documented first at the scene.

Conditional evidence

Evidence created by an action or event, such as a light switched on or a door left open, and it must be documented before anything is moved.

Negative evidence

The documented absence of something expected at a scene, such as no blood where a wound should have bled, which can support or refute a reconstruction.

Chain of custody

A documented record of every transfer of an evidence item, showing each person who handled it, the date and time, and the purpose of the transfer.

Evidence seal signature

The person sealing a package writes a signature or initials across the seal so that any later break in the seal is visible and must be explained.

Contemporaneous notes

Notes written at or near the time of observation that record times, conditions, persons present, and factual observations, forming the foundation for later reports and testimony.

Scene entry log

A written record of every person entering and leaving the scene with name, agency, purpose, and time, used to control contamination and support later testimony.

Grid search pattern

A search method in which the area is swept in parallel lines and then swept again at right angles, giving thorough coverage of small or high-value areas.

Zone search pattern

A search method that divides a large or multi-room scene into sectors, each assigned to a searcher who documents the sector before moving on.

Paper packaging rule

Biological and damp items are packaged in paper so they can dry and breathe, while plastic is reserved for non-biological items needing moisture protection.

Substrate control

A sample of the unstained material adjacent to a stain, collected to show that the surface itself does not react with the test or contain the target substance.

Buccal reference standard

A cheek swab collected from a known person to provide a DNA comparison standard, documented with consent or legal authority and kept under chain of custody.

Presumptive blood test

A screening test such as luminol or Kastle-Meyer that indicates the possible presence of blood, and it must be followed by a confirmatory test.

Touch DNA

Low-template DNA deposited by skin cells on an object, easily contaminated, and collected with clean gloves, a mask, and a focused swab of the contact area.

Angle of impact formula

The angle of impact is derived from sin θ = width divided by length of an elliptical bloodstain, with direction of travel from the round end toward the tail.

Area of origin

An estimate of the three-dimensional point from which blood was projected, obtained by projecting lines through the long axes of stains back to a common region.

Void pattern

An absence of bloodstain where surrounding surfaces are stained, indicating that an object or person blocked the blood at the time of deposition.

Cast-off pattern

A linear trail of blood droplets thrown from a bloody object in motion, used cautiously to interpret direction of travel and the number of swings.

Cyanoacrylate fuming

A fingerprint development method in which superglue vapor polymerizes on latent print residue on non-porous surfaces, often followed by dye staining for contrast.

Ninhydrin development

A reagent that reacts with amino acids in latent print residue on porous surfaces such as paper, producing a purple development visible after time and heat.

Plastic fingerprint

A visible three-dimensional impression left in a soft material such as putty, wax, or fresh paint, documented with oblique lighting and a scale.

Elimination prints

Known prints collected from responders and household members so their prints can be excluded from latent prints of evidentiary value at the scene.

Dental stone casting

A method of preserving footwear or tire impressions in soil or snow by pouring a dental stone mixture, reinforcing it, and documenting orientation with a scale.

3R glass rule

Radial cracks show right angles on the rear or opposite side of impact, which identifies the side from which the glass was broken.

Gunshot residue stubs

Adhesive collection stubs applied to hands and face that detect primer elements, indicating residue presence but not identifying who fired the weapon.

Livor mortis

Postmortem settling of blood in dependent vessels that begins within about one to two hours, becomes fixed in roughly eight to twelve hours, and indicates body position.

Rigor mortis

Postmortem stiffening of muscles that begins in small muscles within about two to four hours, peaks near twelve hours, and resolves in roughly twenty-four to forty-eight hours.

Manner of death

The classification of how death occurred, using the categories natural, accident, suicide, homicide, and undetermined, distinct from cause and mechanism.

Incised wound versus laceration

An incised wound is produced by a sharp edge and is longer than deep, while a laceration from blunt force is deeper than long with tissue bridging.

Daubert standard

A legal test for expert testimony that considers testability, peer review, known error rate, and general acceptance of the method by the relevant field.

Plain view doctrine

A legal rule allowing seizure of evidence without a warrant when an officer is lawfully present, has lawful access, and the evidentiary character is immediately apparent.