It's obvious to the most causal observer that neither of you is done yet. I say this as someone who has been there and done what you are doing, too many times.
Why worry about the fellow junkie with the couch when your son made the decision to use again, while under the SLE roof and did so despite the consequences.
Once busted, he immediately called in his rescue team to prevent him from experiencing the consequences.
I say this as the mother who used a rope to tie my daughter to me to prevent her from stealing more stuff and /or running out the door for her next fix. I understand your need to do something at the exact moment in time when it's probably better to do nothing.