In the context of searching or investigation the word traces is similar find, discover, detect, find, uncover.
The alternatives that are shown in the screen, chains, harness, evidence and tracks i would like to comment their meanings so close to traces.
Chains: a sequence of items of the same type forming a line.
Screen: Something that shelters, protects or hides.
Evidence: Information indicating whether a belief or proposition is true or valid.
Harness: Control and make use of natural resource especially to produce energy.
According these definition the best synonym of traces is evidence.