Is is legal to put out fliers warning people that a person is a drug dealer/thief?

My cousin is a meth addict. He was doing well for a while and came to stay with me. He grew up around here and reconnected with many old friends and family. Now he has fallen off the wagon and has stolen/scammed/etc several people. He has also broken into homes and cars and come close to physical violence. I want to warn people to beware of his behavior but dont know which townhouse belongs to specific elderly people. I don’t have anyway of contacting them and was thinking of putting fliers on the cars in that complex. I don’t want anyone to get hurt including my cousin. If he keeps up his current habits he is going to. Is it legal to post such a thing? Do I put his whole name? Do I use a picture- he has been known to use his brothers name as an alias. What the heck would I write?
It is not slander when it is documented fact. The cops have been called. He was in rehab – that’s why he was doing well. Aiding and abetting?? How so? I am trying to stop him!!