Security Deposit Conflict w/ Old Roommate

[aperture science]

Illinois

Last academic school year, I lived with three roommates in an apartment. This academic school year we all split off into other apartments. The issue is that the security deposit for last year's apartment was sent to one of the roommates only.

At first, this roommate claimed we didn't receive a security deposit. This was believable, since we all trashed the place a bit. But I recently found out that our landlord did, indeed, send him a security deposit for ~$360. In other words, this check should have split equally among the roommates for ~$90 each.

I tried calling this roommate multiple times. He never picked up nor answered my voice messages.

I have a copy of the check that was cashed in (given to me by the landlord). This copy has his signature and his routing number. Thus, I feel I have adequate evidence that he has been lying to us.

Given that I can't get in contact with him, what would be the appropriate action to take? Should I get law enforcement involved?