‘The definition of excessive force’: Policing experts assess the beating of Tyre Nichols.

Experts in police training who reviewed videos released on Friday of the fatal beating of Tyre Nichols in Memphis said they believed there was no justification for the actions of the police officers involved, who have been charged with crimes including second-degree murder in his death.

The footage, which amounts to almost an hour from both police body cameras and street cameras, shows officers beating, kicking and using a baton against Mr. Nichols after he fled a traffic stop.

“In my career, I’ve never seen — I mean, you see it in the movies — but I’ve never seen an individual deliberately being propped up to be beaten,” said Ed Obayashi, a police training expert and lawyer who conducts use-of-force investigations for state law enforcement across the country.

“To me, that’s worse than Rodney King,” added Mr. Obayashi, who is also a deputy sheriff and policy adviser in the Plumas County Sheriff’s Office in California.

In police training, it is emphasized repeatedly to officers that they need to be aware of their physical surroundings, Mr. Obayashi said, but the same stress should be placed on awareness of their own emotions. If officers’ tempers run high, he said, they are bound to make mistakes.

In the Nichols confrontation, it is possible the officers felt disrespected when their directions weren’t followed, he said.

“This appears to be a case of classic contempt of cop,” he said, “for them to catch up with him later and then exact their revenge on the poor individual.”

Chuck Wexler, executive director of the Police Executive Research Forum, an organization of current and former law enforcement officials that studies the improvement of policing, said the officers’ behavior also fell short in other ways.

In modern policing, officers are usually trained to communicate clearly to an individual and respond proportionally to their actions, he said. These officers did neither, he said.

The beating is “the definition of excessive force,” Mr. Wexler said. In his view, Mr. Nichols did not present a danger that matched the force the officers used, beyond appearing to not want to be arrested.

Even when Mr. Nichols was lying on the ground, none of the officers attempted to help him, which Mr. Wexler said was a violation of their duty to render aid.

“This person was not treated as a human being,” he said.