The governor of the western US state of Washington on Wednesday announced a new investigation into the death of a black man who died while in police custody as he pleaded that he couldn't breathe.

"I have become convinced that the Pierce County Sheriff should not complete the investigation of the death of Manuel Ellis and the county prosecutor should not review the investigation and make charging decisions," Governor Jay Inslee said in a statement. 

"Instead, there must be a new investigation and charging decision made independent of Pierce County law enforcement."

Inslee's decision came in the wake of newly obtained surveillance video that showed Ellis crying out while being restrained by police on March 3.

The video was taken from a home security camera across the street of the intersection where he was being detained. A passerby had also captured part of the arrest on video.

In the nearly nine-minute clip released by the attorney representing Ellis's family, the 33-year-old Ellis is heard crying out while handcuffed.

"What we learned from that video is not just that Manny Ellis said, 'I can't breathe,'" the attorney, James Bible, told a news conference on Tuesday. "What we learned is he said, 'I can't breathe, sir. I can't breathe, sir. I can't breathe, sir.

"A clear sign that it's not only a struggle for breath but an attempt to still be respectful in your last moments of life. A sign that he wasn't the aggressive person law enforcement claimed he was."

The mayor of Tacoma, located about 35 miles south of Seattle, last week called for the police officers involved in the arrest to be fired and prosecuted.

Ellis died of respiratory arrest due to hypoxia and physical restraint, according to the medical examiner's office which added that methamphetamine in his system and heart disease could have also been contributing factors.

Inslee's decision to launch a new probe into the case comes amid recent nationwide protests over police brutality and racism sparked by the death of George Floyd while also in police custody in Minnesota on May 25.

"I came to this conclusion in consultation with Attorney General Bob Ferguson after the county prosecutor informed the state late yesterday that the Pierce County Sheriff's department had officers at the scene when Mr. Ellis was detained and died," Inslee said. 

He added that authorities had also learned that a Washington State Patrol trooper had responded to a call for assistance and was at the scene briefly while Ellis was in custody and still alive.

The four officers involved in restraining Ellis have been placed on administrative leave.

The officers said they had tried to arrest Ellis after he allegedly tried "to open car doors of occupied vehicles."

They said a physical altercation took place and Ellis had to be restrained. He died at the scene.

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