Murder by Helmet?

In the wake of last night's important PBS "Frontline" on concussions and the NFL (and  a cover-up), here's a remarkable Sports Illustrated feature on the death of Speedy Cannon, a black running back in Alabama back in early 1970s (when racism was even higher than  today) after being brutally struck with the helmet of a white rival.  Was it an accident? Murder?   They even have a clip of the play.  And the writer meets the kid who launched himself like a missile at Cannon's head.  Still the mystery remains. See if you agree with the writer's conclusion.