Something to make us believe he left important evidence at the scene.
If I let her up here, he thought, whatever happens will leave evidence.
No need to leave evidence of flight to be found by the first person to poke a head in after he went.
Combined, these conditions have left very little physical evidence of the structures.
Using physical force to open the door will leave obvious evidence.
They leave evidence of the presence, which is then discovered by the crew.
So far he hasn't left much forensic evidence at the scene.
Finally, why did he leave evidence of his unresolved decisions for all to see?
Never mind the fact that they've left evidence of their vandalism all over the site.
Several other cultures have also left evidence of their occupation on the island.