Vega's body is lying dead from a GSW in his apartment. The smoke detector is going off. You have to figure the police would be at that crime scene sooner rather than later. The maintenance guy would probably have been called, the manager wants the rent, etc. He thought him and Fabienne would just take the train to Knoxville (where his great-grandfather bought the gold watch) and disappear? The first questions the police would ask are who rented this apartment and where is he now. They would track them down in no time. Also, when Marcellus made that deal with him in the pawn shop, he didn't know at the time he had just killed Vincent. Enough is enough. First his ass doesn't go down in the 5th, then he kills Vinny? Plus 'I think he fucked Mia that one night 'cause they've both been acted weird around each other'. No fucking way Wallace let's this go. He thought he was just going to live in peace in Tennessee?