Illegal Possession Of Firearm

Location: Spokane and Kootenai Counties - WA and Idaho

I have a friend who is in the middle of a break up with a live-in boyfriend. She and this soon to be ex moved in together a few weeks ago in Kootenai County and the relationship quickly broke down. Now she is changing the lease to be only in her name and he is supposed to move out tomorrow.

Complicating matters, we just found out through public records that he has a Domestic Violence felony on his record with a notice of ineligiblity to own firearms as of one year ago. This was against his ex-wife and it looks like he is still on probation for the charges. Also, my friend told us that within the last month the soon to be ex was driving my friend's car by himself, decided to play with his illegally obtained gun while driving, and shot through her windshield. She has since had to pay to have the windshield replaced.

After this incident, she has taken the gun from him and keeps it on herself. He is supposed to move out tomorrow, and she thinks she is just going to give the gun back to him. I think this is stupid.

What are the possible legal ramifications if she does give the gun back knowing he is prohibited from owning a gun? If we report him after he moves out, what are the possible legal ramifications for him having a gun? Would doing so then put my friend in legal trouble? She thinks not giving the gun back would escalate the already tense situation with the move out.