If your friend tells you they are stealing, do you tell someone or keep their trust?
In general one should tell the right people – not to get the friend into trouble, but to help him to get out of his stealing problem.
You are in the delicate position of knowing about a friend’s personal trouble, and you should use your knowledge carefully to try to get him out of it.
Although not easy, this is part of being a friend, and if you inform the right people, he’ll ultimately thank you for it.
Best wishes and good luck.