Plastic bags are present in many criminal cases. They are frequently used by perpetrators of crimes for the disposal of evidence, bodies, or body parts. Even when useful evidence is found inside a bag, sometimes the most important forensic evidence is the bag itself. By analyzing a bag, it is often possible to determine the manufacturer. More importantly, the bag can be compared to bags from a known box or other source to determine whether the bag could have originated from that source.
As with many types of physical evidence, it is important to understand the manufacturing process. This webinar will include a description of how plastic bags are made. Understanding the manufacturing process and the various types of characteristics generated is essential to interpreting the significance of a comparison result. Special emphasis will be placed on class characteristics and randomly acquired characteristics present on the bags.
The next segment will be a discussion on the forensic analysis and comparison of plastic bags. The analysis involves various macroscopic observations, measurements, microscopic observations, and chemical analyses. Some of the most important visual characteristics are extrusion lines that are present in some bags. These lines are best observed with transmitted light. Various techniques of using transmitted light to view these lines will be presented.
The webinar will include aspects of report writing and courtroom testimony. The final segment will discuss recent research in this area, followed by a question-and-answer period.
Detailed Learning Objectives
- Attendees will gain an understanding of the significance of plastic bag examinations in forensic cases.
- Attendees will gain an understanding of the manufacturing process and the various characteristics that can be observed and compared in plastic bag examinations.
- Attendees will learn how to interpret the results of an analysis of plastic bags, which will allow for proper report writing and courtroom testimony.