Three former police officers charged with violating George Floyd’s civil rights were trained on constitutional rights and providing first aid, a court was told.

Kelly McCarthy, chief of police at the Mendota Heights Police Department and chairwoman of Minnesota’s Police Officers Standards and Training Board, said J. Alexander Kuena, Thomas Lane and Tou Thao were all licensed officers in the county and described the training every officer must get.

Asked why officers are specifically taught to reposition someone being restrained face-down to ensure they can breathe, she said: “There were enough in-custody deaths that we needed to have a learning objective on it.”

Kueng, Lane and Thao are accused of depriving Mr Floyd 46, of his civil rights by failing to give him first aid while he was handcuffed, face down, with their colleague Derek Chauvin’s knee pressed onto his neck for almost 10 minutes on May 25 2020.

Kueng knelt on Mr Floyd’s back and Lane held down his legs while Thao kept bystanders back.

Kueng and Thao are also accused of failing to intervene to stop Mr Floyd’s murder, which triggered protests worldwide and a re-examination of racism and policing.

Prosecutors planned to show video from the officers’ body cameras on Friday and provide transcripts for the jury.

On Thursday, the head of the Minneapolis Police Department’s homicide unit told the court the officers should have intervened to stop Chauvin.

He said that can mean intervening to begin first aid or even moving an officer out of the way.

Asked what Chauvin was doing that was significant to him, Lieutenant Richard Zimmerman, the most senior officer in the department, replied: “The knee on the neck – the officers should have intervened at that point and stopped it… It can be deadly.”

Lane’s lawyer, Earl Gray, pointed out while Lt Zimmerman gave evidence that his client is not charged with failing to intervene.

Lt Zimmerman, who joined the department in 1985, also gave evidence at Chauvin’s state trial, which resulted in murder and manslaughter convictions, last year.

The defence said Chauvin was the most senior officer at the scene and argued that the others were trained to obey him.

Lane and Kueng were new recruits, while Thao had been with the force for about eight years.

But rank and seniority don’t change the duty to intervene, Lt Zimmerman said.

“We all wear the same badge,” he said.

Lt Zimmerman also discussed his interviews with the officers immediately after Mr Floyd’s killing.

Prosecutor Samantha Trepel, from the Department of Justice civil rights unit, played a portion of Lane’s body camera video which showed Lt Zimmerman asking Lane and Kueng what happened.

They recounted elements of their struggle to try to put Mr Floyd in their police car after they responded to a report of someone using a counterfeit $20 note.

“He kind of seemed like he was on something.. … He was fighting the whole time,” Lane says.

Lt Zimmerman said Lane and Kueng did not tell him about keeping Mr Floyd on the ground without rolling him over, about Chauvin keeping his knee on Mr Floyd’s neck, about them being unable to find a pulse, or about Lane performing CPR in the ambulance.

Ms Trepel asked if the officers’ obligation to be truthful applied to the account that Lane and Kueng gave him.

Lt Zimmerman said it did.

Mr Gray said Lane is seen on video calling for an ambulance and upgrading the call to lights-and-sirens as Mr Floyd’s condition worsens, asking if they should roll him over and being rebuffed, and expressing concern that Mr Floyd might be experiencing “excited delirium.”

Under cross-examination from Kueng’s lawyer Thomas Plunkett, Lt Zimmerman said he told FBI investigators he thought poorly of Chauvin and “it’s pretty much known throughout the department that he’s a jerk”.

Lt Zimmerman agreed that a “jerk” probably should not be a field training officer, as Chauvin had been to Kueng.

Kueng, who is black, Lane, who is white, and Thao, who is Hmong American, are charged with wilfully depriving Mr Floyd of his constitutional rights while acting under government authority.

The charges allege that the officers’ actions resulted in Mr Floyd’s death.

Chauvin, who is white, pleaded guilty in December to a federal civil rights charge.

Lane, Kueng and Thao also face a separate state trial in June on charges alleging that they aided and abetted murder and manslaughter.