Two of three former Minneapolis police officers charged with violating George Floyd's civil rights confirmed that they plan to testify when their attorneys lay out defenses against allegations that they failed to help Floyd, who died in their custody.

J. Alexander Kueng and Tou Thao told U.S. District Judge Paul Magnuson late Monday afternoon that they plan to take the witness stand in their own defense. Attorney Earl Gray signaled to jurors in his opening statements three weeks ago that his client, Thomas Lane, would testify. However, Gray said Monday that he and Lane would need to think about the matter overnight.

Defense attorneys will begin their cases Tuesday; prosecutors called their last two witnesses Monday. Thao's defense is expected to be presented first, followed by Kueng's and Lane's.

Of the five other Minnesota officers who have been tried in the killing of civilians on the job, four testified on their own behalf.

Derek Chauvin, who knelt on Floyd's neck for more than nine minutes, is the only officer in the case who has not testified at his trial. Jurors convicted Chauvin last April of murdering Floyd. Chauvin later pleaded guilty in federal court to violating Floyd's civil rights.

The prosecution's last witness was Darnella Frazier, who was 17 when she recorded and shared cellphone video of Floyd's arrest. She is widely credited with providing key evidence against the officers charged in his death.

Frazier, now 18, immediately grew emotional as she sat down in the witness chair. She pushed herself back from the witness stand while seated.

"I can't do it," she said in a strained voice as she appeared on the verge of tears. "I'm sorry, I can't."

Court recessed for several minutes before she returned and testified briefly about what she saw.

"I seen two officers and a man on the ground saying, 'I can't breathe,' and he just looked defeated on the ground," Frazier said.

Earlier Monday, prosecutors called University of Virginia use-of-force expert Timothy Longo Sr.. Longo, the associate vice president for safety and security at the university in Charlottesville, said the men failed to care for Floyd when they arrested him on May 25, 2020, for allegedly using a counterfeit $20 bill to buy cigarettes at Cup Foods in south Minneapolis.

Their conduct in restraining Floyd stomach-down in the street was "inconsistent with generally accepted police practices," Longo said.

"I don't think there was any information that suggested that [Floyd] posed a threat," Longo said. "He was handcuffed …"

Longo, also a veteran of the Baltimore Police Department, found fault with how the officers restrained Floyd, their failure to sit or stand him up, and their failure to provide medical aid when he stopped breathing and showed no pulse.

Kueng, Lane and Thao are accused of violating Floyd's constitutional right to be free from unreasonable seizure by failing to provide him aid. Thao and Kueng are also charged with failing to intervene on Floyd's behalf to stop Chauvin's restraint.

Kueng and Lane were the first at the scene. Thao and Chauvin arrived as Kueng and Lane attempted to get Floyd into their squad SUV.

Chauvin pinned Floyd's neck under his knee while Kueng held his midsection and Lane held his legs. Thao monitored a crowd of angry bystanders on the curb.

"I could not see an objective reason to have placed him on the ground," Longo said, adding that it is "inherently dangerous" to leave someone prone on the ground because it can stop their breathing.

Longo said he reviewed Floyd's arrest from the perspective of every officer as well as from a surveillance camera. He said he was not paid for his testimony. Longo covered familiar ground, with experts already having testified about how the restraint of Floyd violated general police and medical policies and practices.

On cross examination, the defense attorneys worked to show that despite not being paid, Longo has close ties to the U.S. Department of Justice as well as Hennepin County prosecutors. He previously testified for the prosecution in the case against former Minneapolis police officer Mohamed Noor, who was convicted of fatally shooting Justine Ruszczyk Damond in 2017.

He also testified for the defense of two Baltimore police officers in the 2015 death of Freddie Gray in the back of a police van.

In a direct manner and tone bordering on exasperation, Longo talked about how the duty of an officer to care for a restrained subject is "absolute" because they're no longer able to take care of themselves.

When another officer is using excessive illegal force, the others have a duty to take "affirmative steps, to do something" to "stop the behavior," he said, adding that the three officers with Chauvin failed that duty.

We've taken an oath to "uphold the law, to protect people, particularly to protect people who can't protect themselves," Longo said.

In one of the loudest, dramatic moments of the trial, Gray yelled at Longo as he questioned him about what Lane should have done.

Lane twice asked about rolling Floyd on his side and was rebuffed by Chauvin's ignoring him or saying no. Longo said asking to roll Floyd over wasn't taking action.

"I think someone should have done something," Longo said.

Gray pressed on, loudly asking whether Lane was supposed to have picked up Chauvin and tossed him aside to start CPR on Floyd.

"They could have put a man who was unresponsive on his side," Longo said. "No one asked Chauvin to get his knee off his neck."

Gray continued, "They asked to roll him over twice, did they not? That was my client. Welcome to Minnesota, I'm done."

The defense has argued that Chauvin was the senior officer on the scene, "the shot-caller," but Longo said the duty to intervene isn't dependent on rank or experience. "It's a responsibility of everyone that's there to do something," he said.

He also testified about the appropriate force that can be used on a suspect, saying "only enough to accomplish the objective" and that factors would include the seriousness of the crime, whether the person was a threat, the environmental conditions and others at the scene.

On cross-examination, defense attorney Robert Paule noted that Longo testified in the Freddie Gray case that it was dangerous for the officer to enter the back of the van where Gray was cuffed with his legs tied. "Your testimony is George Floyd didn't pose" a threat to those officers, Paule said, but added, "People do get out of restraints, particularly handcuffs."

Longo said the cases were too different for comparisons.