What are two methods for collecting comparison footprints from a suspect?

The selection of water-based ink and talc on newspaper as a method for collecting comparison footprints is effective due to the ability to capture fine details of the tread pattern, which is crucial for comparison analysis.

Using this method, the foot with the ink is pressed onto the talc-covered newspaper. The talc helps absorb any excess moisture from the ink, which results in a clear and defined impression of the footprint on the newspaper. This clear impression can then be analyzed and compared to impressions found at the crime scene, aiding in linking the suspect’s footwear to the evidence. The use of water-based ink is also advantageous because it is less likely to smear compared to oil-based inks, making it ideal for producing clean, detailed prints.

This technique is particularly useful in forensic investigations as it allows for the retention of the tread pattern's unique characteristics, which often are pivotal in the analysis and can assist in establishing a suspect's presence at a crime scene.