Sample Crime Scene

Exterior of house

Interior of house

Suspect Vehicle

Exterior of house

Ballistics Evidence

A fired bullet was found on the interior of the residence on the floor of the living room

When a bullet is fired from a gun, the markings visible on the side of the bullet known as striations are formed as the bullet scrapes against the rifling ridges inside the barrel of the gun. Striations are considered individual evidence since each firearm produces unique patterns. The caliber of the weapon used to fire the bullet can be determined by measuring the diameter of the bullet. This is considered class evidence since more than one weapon would have the same caliber

Forensics ballistics analysts would be able to match the fired bullet to the gun that fired it by observing the crime scene bullet to a test fired bullet under a comparison microscope.

Ballistics Evidence Analysis

Impression Evidence

A plastic shoewear impression of a men's size 10 athletic shoe (that did not match any of the home's occupants) was found in the soft dirt of a flower bed next to the driveway in front of the house. The shoe showed significant wear in the ball of the foot area

Documenting impression evidence

• The brand and size of this print would be considered class evidence that would only be able to narrow down suspect pool, however the unique wear pattern is individual evidence that could be matched to a suspect's shoe if recovered.
• Shoeprint evidence is circumstantial because it can imply a fact, but does not directly prove it
• What information can be obtained from this print?
• We can initially predict a suspect's general size and gender, with further matching we can identify the particular suspect by matching individual characterists of the cast to footwear owned by the suspect.

DNA Evidence

DNA evidence was recovered from the passenger window of the suspect's vehicle from a fingerprint smear containing sweat and oils. The DNA matches that of the victim

DNA can be extracted from most biologial samples. This is a form of individual evidence since every person has a unique combination of base pairs that make up their DNA. The sweat and oils that made up the smear on the window would be considered biological evidence since they contain organic matter which contains DNA molecules.

DNA requires laboratory processing to obtain a profile of the individual that can be used for identification purposes. The source of DNA will be run through a process known as gel electrophoresis to separate molecules and develop the

Processing DNA Evidence