[UCANSEE2]

...is there anything else that might lead to that conclusion

My guess is that when he slipped into that building (caught on video), that is when he swallowed the heroin (or whatever he had on him).

Then, while in the police van, he went unconscious and hit his head on the rear door bolts, which may have caused the damage to his neck. IIRC, he was in a coma for a week before he died.

[ArmstedFragg]

He didn’t fall into a coma until the last couple of days.