General:
* Path
* Route
* Track
* Way
* Course
* Line
* Trace
Specific to outdoors:
* Footpath
* Hiking trail
* Walking trail
* Nature trail
* Backcountry trail
* Wilderness trail
Specific to crime or evidence:
* Clue
* Footprint
* Sign
* Evidence
* Mark
Figurative:
* Vestige
* Remnant
* Legacy
* Heritage
The best word to use will depend on the specific situation. Consider the context and what you want to emphasize.