I'll add this from The Guardian.
"Batts confirmed that Gray, who was in leg irons, was not wearing a seatbelt in the vehicle as required by the department’s policy. “There are no excuses for that. Period,” he said. Past prisoners in
Baltimore have died from injuries sustained when they were thrown around the back of police vehicles due to fast or erratic driving and abrupt stops."
The article goes on to say.....
"Davis said Gray said he needed a medic during a third stop by the van, made to pick up a second prisoner, but an ambulance was not called until 25 minutes later, after the vehicle arrived at police headquarters. Batts told reporters that during the third stop, officers “picked him up off the floor and placed him on a seat”.
So it sounds like we do have confirmation that he was deliberately left to bounce around the vehicle.
http://www.theguardian.com/us-news/...backtrack-over-possible-explanation-for-death