I'm 21, my brother's 18, and our parents divorced in 1999. My brother sounds quite similar to your brother, although a little less extreme as for the stealing part. My brother started to become involved in fights more and more often.
As the older sibling, especially in the situation you and I are in, you have an extreme sense of responsibility. You sound like you do. What I have seen in my brother is that he's quite young for his age, and that he needs more time to grow up. That might be the case for your brother, too.
My brother always became extremely hostile when I tried to talk with him about his behavior, I don't know if that's the case for your brother, too... I think most of that aggression came from having the feeling that I wanted to "mother" him, or maybe even because he thought I was disappointed in him.
Essentially, what he's doing is his own responsibility. I think you should not confront him as much with his behavior if that means he becomes hostile towards you. Instead, he needs to know that you love him and that you're there for him, any time he needs you or your help. He needs to grow up, you can only help him with that... He needs to realize what he's doing and most likely, he already knows it.
My brother's been improving a lot, lately (he's nearly 19 now), so perhaps puberty is finally releasing its hold. I hope things will become easier for your brother with time, too.
Perhaps a short time in jail will clear your brother's mind - my brother was put in jail for 2/3 days or so and it scared him to death... ;p.
Remember his life is his responsibility. I really had to remind myself of it over and over... But it's helped me somewhat to gain a more objective view of the situation.
Oh, by the way, does your brother have someone "good" (as in, non-criminal, like a friend from when he was younger) that he can trust and talk with about his personal feelings? That usually helps, too, because they're not as personally involved (like you are).