Why would he start now? 
Sorry, I meant Walt Jr (RJ Mitte).
Jesse’s fingerprints would have been all over the lab and his cell, which of course they had on file from his previous arrests. And his body wouldn’t have been among the dead. The cops arrived within minutes of his escape, so as soon as they did a crime scene analysis they would be looking for him.
Yeah, Walt’s escape from the town in New Hampshire when he didn’t know the area and the cops were combing the area for him, and then making it cross country in a stolen car wasn’t exactly a model of plausibility either.
Surely you mean… FLYNN!