The pt has self-harmed, had one big blade that you've recovered, has stated they are a wanted criminal, and suggested that they are a very nasty character (you name it, I've done it). You've stabilised their condition, putting your own safety at risk, but are you sure you've got all the weapons this person had when they came out tonight? Notifying the Police that you have a patient claiming they are wanted is the quickest way to find out if they are wanted/dangerous/not safe to ride in the back with, or just a pt in need of serious help. You won't know unless you ask. Not checking, and not ascertaining if the pt is a violent criminal before getting in the back of the van with them seems the politically correct but most dangerous route, so I'd say call it in,