I had a similar situation with my younger brother, but fortunately absent the criminal activity. After quitting his umpteenth job in IT right before the tech crash, he found himself in a giant pickle. He had failed out of college and was jobless. He wisely decided to go back to school but had zero money. Because, of course. My husband and I agreed to help him out with an incentive, performance based arrangement.
Every semester, he'd report back his grades. For every credit hour of A, we'd pay him IIRC $60. For every credit hour of Bs, $30. $15 for C+. Nothing for less than that. We'd total it up and pay it out in 4 equal payments. There was a $1000 bonus for graduation. This way he had cash for necessities and the better his grades, the more cash he earned. He did graduate and went on to get his Masters.
I'm happy to report he appears to have gotten his shit together.
Maybe something like that would work? Maybe a matching program for savings or something? It's important that they earn it from making good decisions.