How is plastic evidence preserved at a crime scene?
Plastic evidence is preserved at a crime scene by carefully collecting it in non-reactive containers or bags to avoid contamination or degradation. It is labeled properly and submitted to a forensic lab promptly for analysis, ensuring minimal exposure to environmental elements, as plastic can be sensitive to heat and chemical interactions.
How is plastic evidence collected and documented at a crime scene?
Plastic evidence is collected by first securing the crime scene to prevent contamination. Investigators wear gloves to handle the evidence, placing it in sterile containers or bags. They document the evidence through detailed notes, photography, and sketches, ensuring chain of custody is maintained throughout the process.
What techniques are used to analyze plastic evidence in forensic investigations?
Techniques used to analyze plastic evidence include microscopy to examine physical characteristics, spectroscopy (such as FTIR and Raman) for chemical composition, gas chromatography-mass spectrometry (GC-MS) for identifying polymers and additives, and comparison with databases for source determination.
How can plastic evidence be used to establish a timeline of events in a criminal investigation?
Plastic evidence can help establish a timeline by analyzing manufacturing dates, patterns of wear, or degradation. It can link suspects or victims to specific items at particular times. Forensic analysis of tool marks, prints, or residues on plastics can also indicate the sequence of events in a crime.
What are the challenges in presenting plastic evidence in court?
The challenges in presenting plastic evidence in court include ensuring its authenticity, preventing tampering, dealing with potential degradation over time, and maintaining a clear chain of custody. Additionally, interpreting microscopic or trace plastic evidence can be complex, requiring expert testimony that may complicate proceedings.