Forensic Science

Primary Crime Scene

Where the crime first occured

Secondary Crime Scene

Any crime scene coming after the primary

Parallel Line/Strip Search Method

Often to find a missing child in a forest area. Shoulder to shoulder, walk in a line.

Grid/Double Line Search

Good for looking for small items, but also time consuming. Search by grid system.

Zone Method

Divide room/building into zones and search systematically.

Spiral Search

Often used in open ocean or to find a small piece of evidence you suspect is nearby. Either start where you think it happened and spiral outward or vice versa.

Wheel/Ray Method

People start in the center and go outward in lines (looks like spokes of a wheel)

Link Method

Examine physical evidence at scene and make links to follow the chain of evidence, searching accordingly

IAFIS

Integrated Automated Fingerprint Identification System

CODIS

Combined DNA Index System

Locard Exchange Principle

Objects in proximity exchange matter mutually (e.g. sweater fibers getting on the door)

Corpus Delicti

The essential facts of the crime—what it was, how it was done, etc. Allows for reconstructing the crime by finding out how it was done.

Paper Bags

More breathable. Put evidence in these that will otherwise collect mold. Used much more widely than plastic bags.

Chain of Custody Document

Attached to evidence and records everyone who handles/delivers it.

Evidence Log

Lists all evidence leaving the crime scene

Seven Steps for Response at Crime Scene

1. Assist victims if alive

2. Search for and arrest suspects still on-site

3. Detain witnesses on site and keep them separated

4. Secure the crime scene

5. Start a crime scene security log

6. Record the crime scene (photos, videos, sketches) WITHOUT disturbing anything

7. Collect and preserve all physical evidence

Photo Documentation of Crime Scene

Wide angle

Midrange

Close up

Baseline Measurement

Two fixed structures. Evidence is recorded as point on the line perpendicular to the line segment between the two fixed structures. Record distance from both fixed structures to the ray where the evidence goes and the distance from the ray to the evidence.Used indoors.

Polar/Compass Coordinates

Usually used for unearthed evidence at crime scenes. Uses angle created by ray and line segment connecting fixed points A and B. Record distance from the line segment to the end of the ray going to the evidence. Often used to show the location of a body.

Triangulation

Two fixed points on a baseline. Measure the evidence from both points, creating a triangle. Record interior angles created and distance on all sides. Used outdoors and when the evidence is >10 meters from the baseline.