Fingerprint Evidence Collection and Analysis

Fingerprint evidence plays a crucial role in criminal investigations due to its uniqueness to each individual. This section outlines the methods of evidence collection in forensic science specifically for fingerprints, including finger, palm, toe, and sole prints.

There are three types of fingerprints that investigators may encounter:

1. Latent prints: Invisible marks left on surfaces, made visible through UV light or dusting with magnesium powder. These are photographed and lifted using adhesive strips.

2. Patent (or positive) prints: Visible to the naked eye, often left in substances like blood, ink, or dust. These should be preserved in their original state if possible and photographed for analysis.

3. Plastic prints: Three-dimensional impressions made in soft materials like clay or putty. These should be photographed and, if possible, a mould should be made to preserve the impression.

Vocabulary: Latent prints - Invisible fingerprints that require special techniques to visualize.

Example: A burglar might leave latent fingerprints on a window frame, which can be revealed by dusting with fingerprint powder.

The process of collecting and analyzing fingerprints is a critical aspect of the 7 steps of a crime scene investigation. Proper handling and preservation of fingerprint evidence is essential to maintain its integrity for court proceedings.

Highlight: Fingerprints are unique to each person, making them valuable identification evidence in criminal investigations.

This section underscores the importance of following proper evidence collection procedures to ensure that fingerprint evidence remains uncontaminated and admissible in court. It also demonstrates how different types of fingerprints require specific collection and preservation techniques, illustrating the complexity of forensic evidence handling.

Types of Evidence and Their Processing

Crime scene investigation relies heavily on the proper collection and handling of evidence. This section explains the two main categories of evidence: physical and testimonial. Physical evidence, also known as real evidence, includes tangible items found at the crime scene such as DNA, weapons, and stolen goods. Testimonial evidence comprises written or oral statements from victims, witnesses, experts, and defendants.

Highlight: The process of collecting and storing evidence must be done with utmost care to ensure its admissibility in court.

The concept of Locard's exchange principle is introduced, which forms the foundation of forensic science. This principle states that every contact leaves a trace, meaning that material from the crime scene will be present on the offender and vice versa.

Quote: "Wherever the offender steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him." - Kirk

The document emphasizes the importance of proper evidence collection, transfer, and storage to avoid contamination. Investigators often wear protective clothing, especially in serious crimes like murder or rape, to prevent contamination and protect themselves from hazardous substances.

Vocabulary: Contamination - The introduction of unwanted substances or materials that can compromise the integrity of evidence.

Various types of physical evidence are discussed, including bodily fluids and tissues. DNA can be extracted from blood, semen, saliva, skin flakes, and hair, making these valuable sources for identification.

Example: In a sexual assault case, swabs taken from the victim by a police doctor can provide crucial DNA evidence for analysis.