A black man who died during an attempted arrest in North Carolina was shot five times by police, including once in the back of the head, his family’s lawyers say.

An independent post-mortem found 42-year-old Andrew Brown Jr was killed by a bullet in the rear of the skull as he drove away from sheriff’s deputies, according to his relatives’ legal team.

The FBI says it is opening a federal civil rights investigation into the 21 April shooting in Elizabeth City, adding it would work with prosecutors in the US Department of Justice to “determine whether federal laws were violated”.

And North Carolina Governor Roy Cooper has called for a special prosecutor to be appointed to take over the state’s investigation.

The Brown family’s lawyers claim he was struck by four bullets to his right arm before the fatal shot in the head.

Seven sheriff’s deputies involved in the incident have been put on administrative leave, according to the office of Pasquotank County Sheriff Tommy Wooten.

He said deputies were trying to serve Brown with search and arrest warrants relating to a drug charge and that the incident was over in less than 30 seconds.

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Brown’s relatives have questioned why sheriff’s deputies used deadly force.

His son, Khalil Ferebee, told reporters: “Yesterday, I said he was executed. This autopsy report shows me that was correct.”

The family’s lawyers also called his killing an “execution”, saying deputies continued firing their weapons at him after he drove his car away from them.

The legal team has also accused officials of withholding evidence after being shown only 20 seconds of footage from one police body camera on Monday.

Lawyer Ben Crump suggested there was video from at least nine cameras, including multiple police bodycam and dashcam footage, but that Pasquotank County lawyer Michael Cox had not shown more evidence to the family.

The official post-mortem report from the coroner’s office has yet to be released, but the death certificate indicated Brown died of a gunshot to the skull.

“It was a ‘kill’ shot to the back of the head,” said Mr Crump, citing the private post-mortem carried out by Brent Hall, a former medical examiner in Boone, North Carolina.

“It went into the base of the neck, bottom of the skull and got lost in his brain. That was the cause of death.”

At a news conference, some of Brown’s relatives were joined by mothers who sons were killed in police incidents.

They condemned his death.

“This is what they do in the black and brown communities. They come to us, they brutalise, they terrorise, they kill,” said Gwen Carr, the mother of Eric Garner who died after he was held in a chokehold by an officer.

“It’s horrible what they do to us. And it has to stop. It has to stop,” Ms Carr added.

Brown’s death led to several nights of protests in Elizabeth City.

And it came one day after former Minneapolis police officer Derek Chauvin was convicted of murdering George Floyd in a trial that put a spotlight on police violence against black people.