In hundreds of deaths where police used force meant to stop someone without killing them, officers violated well-known guidelines for safely restraining and subduing people — not simply once or twice, but multiple times.

Most violations involved pinning people facedown in ways that could restrict their breathing or stunning them repeatedly with Tasers, an Associated Press investigation found.

Some officers had little choice but to break policing best practices — safety guidelines that are recommended by government agencies, law enforcement groups and training experts — to save a life or protect someone.

Many other violations were harder to explain. Officers at times prematurely resorted to weapons or physical holds during routine calls or misread a person’s confusion as defiance in medical emergencies, setting off a string of mistakes. In other cases, they kept applying force even after they had people handcuffed and controlled.