Neck restraints by Minneapolis police have left 44 unconscious since 2015

George Floyd protests erupt across the US.Several U.S. cities endured a night of unrest in response to the killing of George Floyd by a white police officer in Minneapolis on Monday.Protests occurred in NYC, Denver, Columbus, Memphis, Phoenix and Louisville.Protests in Minneapolis led to thetorching of a police precinctlate Thursday night.Members of a CNN news crew who were reporting on the scene early Friday were arrested by police on live television. No explanation was given for their arres

Minneapolis Police Department officers have used neck restraints at least 237 times since 2015 and rendered 44 suspects unconscious with the maneuver, according to an examination of police records by NBC News.

The department's use-of-force records reveal that 16% of the incidents in which the tactic was used ended with an individual losing consciousness, the network reported.

About 60% of those subjected to neck restraints and then rendered unconscious were black, the data showed. About 30% were white; only two were Native Americans, and 75% were men, most of them 40 or younger.

While criminal justice experts consider the totals to be unusual, NBC said it did not have immediately available data from other departments nationally to compare with Minneapolis.

According to current policies, neck restraints or chokeholds can be applied using an arm or leg, but the maneuver is not supposed to inhibit a person's ability to breathe.

A week ago, bystanders filmed Minneapolis Police Officer Derek Chauvin kneeling on the neck of a handcuffed George Floyd for nearly nine minutes — including nearly three minutes after he had stopped breathing, according to reports.

He later died at the hospital.

More than a dozen law enforcement experts who analyzed the footage told NBC News that Chauvin was not using a sanctioned maneuver that is taught by any agency.

Many police departments around the country have restricted the use of neck restraints or have banned them altogether.

Chauvin was charged Friday with third-degree murder and manslaughter in Floyd’s death. The remaining three officers on the scene have been fired and could also face charges as the matter continues to be investigated.

A Minneapolis city official also said Chauvin's restraint on Floyd is not permitted by the Minneapolis Police Department, NBC reported.

But the department's online policy manual provides guidance for neck restraints that could render suspects unconscious, NBC reported. And the manual appears to have not been updated for more than eight years.

The  manual reads, "The unconscious neck restraint shall only be applied … 1. On a subject who is exhibiting active aggression, or; 2. For life saving purposes, or; 3. On a subject who is exhibiting active resistance in order to gain control of the subject; and if lesser attempts at control have been or would likely be ineffective."

The passage includes a date in parentheses, April 16, 2012. The front of the manual is dated July 28, 2016.

The department’s data shows most of the suspects who lost consciousness were either fleeing on foot or resisting arrest, and often were injured during the scuffle with police.

Also notably, most of the incidents in which an officer used a chokehold stemmed from a nonviolent offense. Officers were assaulted in five of the cases, NBC reported.