Not much reasoning behind this thinking,
- There in nothing "normal" about killing
- Weather a car ir legally registered or not, A function intelligence apparatus should be able to trace any vehicle used in crime.
- Crime scene evidence does not rely on one legal to result in successful prosecution, if it depended on legality surely then all those killings happening everyday (51- 70 according to stats) majority would be in prison.
Get that fallacy out of your head that just becasue you have an ID or passport or fingerprinted before, if you commit a crime you will traced instantly. You won't, The police incompetence is staggering.