Final answer:
Investigators look for unique characteristics in impression evidence to make connections between items owned by a suspect and evidence at a crime scene, with tools like DNA fingerprinting playing a critical role.
Step-by-step explanation:
Investigators analyze the impression evidence to find unique characteristics to link items found in a suspect's possession to evidence at the crime scene. Impression evidence such as fingerprints, shoe prints, tire tracks, or tool marks can be matched to those of a suspect, highlighting characteristics that are distinctive to a particular item.
For example, unique tread patterns on shoes or tires can leave impressions at a crime scene that can be compared to those of a suspect's belongings. Similarly, DNA evidence has proven crucial, as seen in the case where Dr. Alec Jeffreys of Leicester University used DNA fingerprinting to help in an immigration case, establishing familial relationships through DNA matching. These techniques are valuable in forensic science for establishing links between suspects and criminal activities.