I Have A Patient Whose Mother Confimred She Watches Him

I have a patient whose mother confimred she watches him take his klonopin and suboxone daily but he has tested negative on his drug tests. How is this possible? Can there be a reason for this. Addicts lie and scam but I watched this man go through bad withdrawals until they decided to medicate him and now he is much better. He has been very compliant with everything and talks about his issues. I believe him and so do his peers.