On Dec. 22, 1984, four black teenagers approached electronics specialist Bernhard Goetz, 37, on the New York City subway. After one of them said, “Give me five dollars,” Goetz pulled out a five-shot revolver and opened fire, injuring all four. Of these, one suffered a severed spinal cord, paralyzing him.

In the trial of Daniel Penny, a man accused of killing a homeless and mentally ill man on the New York City subway, jurors are hearing from experts on chokeholds following an admission from a key witness that he lied to police.