Suggest the parents spend time with the boy. This applies to both father and mother, but should be done separately, as not all activities are suitable for the parents as a pair (mom may like mall outings, father may like eating out.
On the subject of eating out, don’t suggest places that he is likely to be seen by his friends. Splurge for a $35-50 meal and take him to a place that shows him he is worth it. (I did it, and it opened my kid like a book.)
And the worst thing you can say to a kid like this is “think about what people will say when they see you with friends like that.”
Instead, focus on “will these friends help you achieve the goals you have for yourself?” This builds his self esteem, which is most likely not great right now.
And remember: they are not “bad kids”; they are kids doing bad things. Big difference, and it should be stressed.