Maybe they were trying to steal his wallet and something went wrong.

"So you know the story about the guy who stole my wallet."

"Are you sure that was the same fellow who stole your wallet?"

The idiot had his wallet stolen right before I found him.

Like the other day, I thought someone had stolen my wallet.

Please go into the men's room with me so I can steal your wallet.

He had his wallet stolen on a recent holiday*.

"Someone stole my wallet at the bus station," he said.

They're the big guy who tries to convince you that he's on your side while he steals the other guy's wallet.