Final answer:
In the Meredith Kercher case, DNA evidence served as a key piece of trace evidence, analogous to trace elements in other forensic cases that help construct the sequence of events in a crime.
Step-by-step explanation:
One key piece of trace evidence in the case of Meredith Kercher involved DNA evidence. Similar to the case of Jean Gianini, who left behind a button at a crime scene, trace evidence can be critical in linking a suspect to a crime. In modern forensic science, DNA analysis plays a vital role, as in the case where Dr. Alec Jeffreys used DNA fingerprinting to solve an immigration dispute by confirming familial relationships. In the instance of Kercher, DNA found at the scene would have been crucial in piecing together the events and identifying the perpetrator. Just as in chemistry, where observable properties are used to theorize about the unobservable, in forensics, material traces are used to build a narrative of events that were not witnessed directly.