Investigators believe Freddie Gray suffered serious head injuries while he was in a police transport van, although they have not concluded how the injuries occurred, according to a law enforcement official familiar with the investigation. One wound occurred when Gray struck his head on a bolt that jutted out in the van, the official said, but that was not Gray’s only head injury. And the injuries overall are consistent with what medical examiners often see in car collisions, the official said.

The findings, which have not been publicly released, are part of an investigation into Gray’s death that Baltimore police handed over to prosecutors Thursday. The new information leaves many unanswered questions for a city roiled by riots and unrest after the 25-year-old’s death from injuries that occurred while in police custody.