He was fatally injured in the van. That doesn't mean he wasn't initially injured during the arrest.
No-one said his neck got "stomped on". It doesn't take a stomping for someone to fracture their neck (especially if they've had lead exposure, which Gray had - it causes bones to brittle). As I've posted before, there's a reason car accident victims and the like are immobolised in case of neck trauma. You can have a fractured neck and walk well enough (though Gray wasn't walking well) and talk (or scream in pain, like Gray), but it if you move a person with a fractured neck the wrong way, jostle them at the wrong angle, you can cause the bones to sever the spinal column.
The video I saw, a close up of the arrest scene, clearly shows at least one of his legs being released from somewhere over his back and falling down from that position. I will post this news item when I find the link again.
FG ran from the cops. He refused to stop when he was being chased. So if he was taken down in a rough fashion, it was on him. After being stopped he continued to resist arrest and was struggling with them and screaming. So if he was injured, it is partially his own fault. How do you grab someone and stop them from resisting with out using some force?
And we have heard that FG had long term damage from lead poisoning since childhood, which often causes damage to ones bone strength. It weakens bones in later life.
So if the cops were forced, by FG himself, to chase him and take him to the ground, and to struggle with him, to arrest him, then it might have been accidental if he had damage to his spine. His bones are compromised from childhood, and he was using drugs for years.
I am not going to jump on the bandwagon and accuse them of killing him, unless I see some evidence of them being out of control. Right now it appears to me that it was just a perfect storm of bad circumstances. And much of the bad situation was set off by FG's own bad choices. JMO
Lead has been linked to problems with the development and health of bones. At high levels, lead can result in slowed growth in children.
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Studies have shown increased likelihood of osteoporosis (weakened bones later in life) in animals exposed to lead. A review of this issue can be found in Puzas (1992). Although this link has not been established in humans, it is likely that upon closer examination of lead-exposed individuals, lead will be shown to be a new risk factor for the disease.
Research currently underway may provide more information about potential impacts of lead on osteoporosis (bone health) in the future."
http://www.atsdr.cdc.gov/csem/csem.asp?csem=7&po=10