Well if he swallowed heroin that could explain how it all happened. He ODed and went into violent convulsions. Remember how River Phoenix died from a speed ball. Was so dramatic that even Christina Applegate apparently acted out the convulsions once for some stupid event.
And if he’s having violent convulsions that would explain his body swinging all over the place in the van..a metal van with a drugged out suspect, could explain the injuries..now it doesn’t explain the cops not helping him or securing him in the van, they should have done that for him or gotten him medical assistance when they noticed something wasn’t right but I dont believe they killed him