cover up one's tracks
{v. phr.}
1. To hide and not leave anything, especially foot marks, to show where you have been, so that no one can follow you.
The deer covered his tracks by running in a stream.

2. {informal} To hide or not say where you have been or what you have done; not tell why you do something or what you plan to do.
The boys covered their tracks when they went swimming by saying that they were going for a walk.
Compare: COVER UP(1).

[TahlilGaran] English Idioms Dictionary ▲