Easy ways for their to be evidence without a crime:

Small kitchen scales.
Bank records and transactions.
Phone records.
A cell phone.
Cash.
Legally prescribed drugs.
Legally owned firearms.
Anything that the police suspect might have DNA evidence on it.

All of the above might be collected by police as evidence, and turn out not to be related to any crime whatsoever, and no crime needs to be committed— just one thought to have been committed.

This is really not hard to figure out.