If they have no way of knowing and he just kept going after being tased. He was on something for sure.
Not necessarily. One of the dirty little secrets of the Taser is that there is a significant portion of the population that the thing just doesn’t work on, even if they are totally sober and have taken no meds. There’s video out there of people not on drugs being tased repeatedly with no effect. These people simply have a neural and nervous system that ignores the taser pulses.