Very sorry that you are going through all of this. There were many times I wish we'd called the police, not necessarily for theft, but acting out of control, usuallly because he took something that caused this. My final straw was finding him on the floor in his room, couldn't wake him up, and a needle was next to him. That's how I found out he was doing herion, not to mention much more than that.
My difficult child just turned 18, but also agreed to intensive outpatient rehab and has been going for about 2 weeks. We were very close to showing him the door too - just hope he sticks with the rehab.
Thoughts are with you. Whatever you decide will be the right decision for you at this time.