Could his neck have been broken from being tossed into the van and the thumping heard was him just flopping around?
I agree the neck can easily be broken inadvertently. A couple of years ago, I found my neck was severely strained just from sleeping. It literally felt like it was almost broken it was that painful and stiff.
I got a fractured neck at a stoplight from a drunk driver and I would never expect the kind of damage I had from that.