Bite Mark and Teeth Impression Evidence

How do forensics investigators use bite mark evidence? Analyze bite marks for characteristics to identify victims or suspects or exclude others. Marks can be left on a victim’s skin or other objects, such as Styrofoam cups, gum, or foods. Saliva or blood may be left behind that can be tested for DNA. Dental records including x-rays can also provide useful information, especially when attempting to identify a victim.

Individual Evidence Bite marks, like fingerprints, are unique to an individual. Forensic odontologists will make a cast or take pictures of the bite marks  

Bite Mark Evidence Collection Photograph the area with a ruler near the injury (in color and B&W). Area is swabbed for traces of saliva (may contain DNA) Area is swabbed for microorganisms Impressions of the bite mark are made

Measurements Investigators take careful measurements of the bite marks These measurements can later be compared to a victim or suspect

Development of a child’s teeth can help estimate the age of a young victim.

A human bite mark will be elliptical or circular and Will display the specific characteristics of the teeth  

The dark markings identify specific characteristics. Fillings, caps, chips, evidence of dental work

Types of Bites clear impression means that there was significant pressure; Obvious bite signifies medium pressure noticeable impression means that the biter used violent pressure to bite down.

Clear Obvious noticeable  

Food can be evidence Investigators can compare the bite patterns on the food to a known sample.

Matching mold to bite mark

Analysis of Bite Mark

Class Characteristics Shape of arch Tooth alignment Thickness Width Spacing Missing teeth Other unique features

Terminology Positive identification-exact match Possible identification-consistencies exist, but not enough to make an exact match Insufficient evidence-not enough evidence to make a determination Exclusion-does NOT match

Serial Killer Ted Bundy Impressions being made of Bundy’s teeth.

Part 1: Make an Impression 1 – Fold the Styrofoam plate in half. 2 – Label one side MAXILLA and the other MANDIBLE. 3 – Gently bite down on the plate to leave your bite mark impression. 4 – Place a sheet of the plastic film over the impression and use a permanent marker to recreate the pattern to match that of your bite mark. 5 – Use a ruler to make the measurements shown and record in the table below along with any notes regarding unique characteristics you observe in the teeth. Maxilla Mandible Depth Maxilla Width Mandible http://forensicfact.files.wordpress.com/2008/05/cast_negative_resized_copy.jpg