Not every perp winds up dead. If you have a person in your custody, who seeks medical attention, and you refuse to provide or request that medical attention, and the person in your custody dies....well....you’re screwed.
That’s the chance you take.
Except, medical attention WAS requested by the driver.
When a doper high on drugs tries to hurt himself, there is little anyone can do,. And he was probably trying to ram through the back door.
This was self inflicted.