Class Class

Class

• Class

• Any characteristics that are common to a group are called class characteristics.

Evidence that can be traced back to a class/group source…

• Evidence that can be traced back to a class/group source…

• Type of fiber is a class characteristic.

• Since there are many thousands of yards of polyester made, even in specific shapes and colors, this is a class characteristic—all polyester fiber has the same chemical characteristics.

Human hair?

• Human hair?

• has the same class characteristics, under a microscope. Their medullas are fragmented or absent and the color and scale pattern of the hair found on any individual varies over their entire scalp.

Individual

• Individual

• Individual characteristics are those that are unique to a single person or a specific item that only one person can possess.

Any evidence that can be traced back to one source (person or object)…

• Any evidence that can be traced back to one source (person or object)…

• For instance, the brown human hair that was a class characteristic on it has a root on can give the DNA of a specific person.

DNA is an individual characteristic.

• DNA is an individual characteristic.

• Fingerprints are an individual characteristic. Since fingerprints are a random growth pattern on an individual’s skin, and they do not change over time, no two people have identical fingerprints

Footwear that has been worn for a few days has individual characteristics.

• Footwear that has been worn for a few days has individual characteristics.

• How is it determined whether a characteristic is class or individual?

The investigator must determine how much of that substance or object were produced and how much of it may be found still in existence.

• The investigator must determine how much of that substance or object were produced and how much of it may be found still in existence.

• The probability of finding another sample exactly like the one in question can then be calculated.

• That probability is used to determine whether or not that questioned evidence has individual or class characteristics.

1. Several pieces of torn T-shirt were found close to a homicide victim. A torn T-shirt was found in the suspect’s bedroom. Can the torn T-shirt and the pieces be individualized. Explain.

• 1. Several pieces of torn T-shirt were found close to a homicide victim. A torn T-shirt was found in the suspect’s bedroom. Can the torn T-shirt and the pieces be individualized. Explain.

At the scene of a robbery a partial note was found on a torn piece of paper. A similar piece of torn paper, that seemed to complete the original sheet of paper and note, was found at the suspect’s office. Can these torn pieces of paper be individualized to each other? Explain.

• At the scene of a robbery a partial note was found on a torn piece of paper. A similar piece of torn paper, that seemed to complete the original sheet of paper and note, was found at the suspect’s office. Can these torn pieces of paper be individualized to each other? Explain.

Several tabs from soda cans were found in a suspect’s kitchen. A soda can was found at the scene of the crime that could be uniquely associated with one of the tabs. How is this possible?

• Several tabs from soda cans were found in a suspect’s kitchen. A soda can was found at the scene of the crime that could be uniquely associated with one of the tabs. How is this possible?

A gun was found in a suspect’s car, these bullets were retrieved from the murder scene. Can these bullets be individualized to the gun? Explain.

• A gun was found in a suspect’s car, these bullets were retrieved from the murder scene. Can these bullets be individualized to the gun? Explain.

The sports section of the newspaper was found at a robbery scene. The finance section was found at the suspect’s office. Was the finance section individual or class evidence? Explain.

• The sports section of the newspaper was found at a robbery scene. The finance section was found at the suspect’s office. Was the finance section individual or class evidence? Explain.