Does poverty cause crime? Or does crime cause poverty?

Interesting article about violence and crime in the inner city over at PJ Media:

My brother drove a chemical tanker in Chicago. He was a big, powerful man who had been an amateur boxer. One day, while he was setting up his hoses on the south side to pump chemicals into a factory’s tanks, a group of teenagers surrounded him and demanded his money. He carried a spiked billy club for such purposes and instead of producing his wallet produced a lesson in night stick justice. When he returned to his yard, he told his dispatcher that he’d never deliver to that business again. Next time, he said, the kids might have guns and a shot would explode the flammable chemical truck and take out a city block.