“Police had said in a court filing that the second passenger reported hearing Gray banging and kicking through the metal divider before the fifth stop. Allan said that would not have been possible given Gray’s injuries, but he may have been suffering a seizure at the time, which could have caused the noise, she said.”
Allan is the M.E.
But:
The medical examiner concluded that Gray’s most significant injury was to the lower left part of his head. Given the descriptions of his demeanor and positioning in the van, it most likely occurred after the second and before fourth stops made by the van driver, and possibly before the third stop, according to the autopsy.
In other words, the convulsing you are referring to took place AFTER he was injured, and therefore (a) had nothing to do with causing the injury, and (b) may have in fact been caused BY the injury.