PHOENIX, AZ — A 44-year-old man climbed onto the roof of his apartment and began acting strangely. Police arrived to help him down, but instead ended up killing him.

Michael Angel Ruiz had a history of drug addiction. On July 28, for reasons unknown, he climbed onto the roof of his apartment. Witnesses called the police to protect his safety. This turned out to have been a fatal decision.

First they tased him several times on the roof. He finally complied and hopped down. Cops immediately swarmed him and put him in a choke-hold.

Witness Gary Carthen said that Ruiz was "getting choked out and tased at the same time." He remained in a choke-hold for at least three minutes.

The most disturbing moments were to come. Michael Ruiz, now fully restrained, was dragged down the concrete stairs on his face. As deputies held his arms behind his back, they allowed his head to dangle and thump against every stair. At this point Ruiz may have already lost consciousness, and was making no attempt to lift his head. Video shows him lifelessly suffering head trauma on the descent down the stair case.

"I just felt sick to my stomach," said Richard Erickson, a retired police detective. "I'd never seen anything like this before, even when I was with the police department."