Prosecutors are asking a judge to give former police officer Derek Chauvin a more severe penalty than state guidelines call for when he is sentenced in June for George Floyd’s death.

The prosecutors argued in court documents filed on Friday that Mr Floyd was particularly vulnerable and Chauvin abused his authority as a police officer.

Defence lawyer Eric Nelson is opposing a tougher sentence, saying the state failed to prove those aggravating factors, among others, existed when Chauvin arrested Mr Floyd on May 25.

Chauvin, who is white, was convicted last week of second-degree unintentional murder, third-degree murder and second-degree manslaughter for pressing his knee against Mr Floyd’s neck for 9-1/2 minutes as the black man said he could not breathe and went motionless.

Although he was found guilty of three counts, under Minnesota statutes he will only be sentenced on the most serious one — second-degree murder. While that count carries a maximum sentence of 40 years, experts say he will not receive that a term that lengthy.

Prosecutors did not specify how much time they would seek for Chauvin.

Under Minnesota sentencing guidelines, the presumptive sentence for second-degree unintentional murder for someone with no criminal record like Chauvin would be 12-1/2 years.

Judges can sentence a person to as little as 10 years and eight months or as much as 15 years and still be within the advisory guideline range.

To go above that, Judge Peter Cahill would have to find there were “aggravating factors”, and even if those are found, legal experts have said Chauvin would likely face a maximum of 30 years.

In legal briefs filed on Friday, prosecutors said Chauvin should be sentenced above the guideline range because Mr Floyd was particularly vulnerable, with his hands cuffed behind his back as he was face-down on the ground. They noted Chauvin held his position even after Mr Floyd became unresponsive and officers knew he had no pulse.

Prosecutors also said Chauvin treated Mr Floyd with particular cruelty during the lengthy restraint, and that he abused his position of authority as a police officer.

They also wrote that Chauvin committed his crime as part of a group, and that he pinned Mr Floyd down in the presence of children — including a nine-year-old girl who testified at trial that watching the restraint made her “sad and kind of mad”.

Mr Nelson disagreed, writing: “Mr Chauvin entered into the officers’ encounter with Mr Floyd with legal authority to assist in effecting the lawful arrest of an actively-resisting criminal suspect. Mr Chauvin was authorised, under Minnesota law, to use reasonable force to do so.”

Mr Nelson said Mr Floyd was not particularly vulnerable, saying he was a large man who was struggling with officers. He wrote that courts have typically found particular vulnerability if the victims are young, or perhaps sleeping, when a crime occurs.

Mr Floyd was not treated with particular cruelty, Mr Nelson wrote, adding the state had not proved that any of the other officers actively participated in the crime for which Chauvin was convicted. He also wrote the presence of children in this case was different from cases in which children might be witnessing a crime in a home and unable to leave.

And, he said, the state failed to prove that Chauvin’s role as a police officer was an aggravating factor, saying Mr Floyd’s struggle with officers showed Chauvin’s authority was irrelevant to Mr Floyd.