The killing of North Carolina black man Andrew Brown has been called an "execution" and an "assassination" by his family's lawyers.
An independent autopsy has revealed Brown, who died last Wednesday during an attempted arrest, was shot five times by police - including once in the back of the head.
Brown's family commissioned a forensic pathologist, who found that Brown's immediate cause of death was a penetrating gunshot wound to the head.
The 42-year-old was shot once in his head, once in his right shoulder, twice in his upper right arm and once more around his right elbow, NBC News reported.
An attorney for Brown's family, Wayne Kendall, told The Guardian the actions of the officers is an "execution".
"This, in fact, was a fatal wound to the back of Mr Brown's head as he was leaving the site trying to evade being shot at by these particular law enforcement officers that we believe did nothing but a straight-up execution."
Lawyer Chantel Cherry-Lassiter told The Guardian it is a painful time for Brown's family and the community.
"This is painful, for his family and this community. This was execution, an assassination of this unarmed black man."
Brown was shot by officers serving drug-related search warrants as well as arrest warrants for Brown in Elizabeth City. Officers were looking for drugs, specifically cocaine, in Brown's house and two of his vehicles.
The FBI announced it was opening a federal civil rights investigation.
Brown's killing has seen days of protests calling for justice and transparency from police, with protesters demanding the full release of the body-camera footage.
Brown's family were allowed to see just 20 seconds from a single officer's body camera of the deadly encounter and their lawyers have accused authorities of hiding video evidence, The Guardian reported.
A court hearing on access to the video is due to take place this week but could take up to weeks for the full legal process to play out.
Khalil Ferebee, Brown's son, told NBC News the video showed that his father posed no threat to deputies, making deadly force unnecessary.
"It's obvious he was trying to get away. It's obvious, and they're going to shoot him in the back of the head? That shits not right. That's not right at all, man"
The killing of Brown comes at a time of already heightened tensions regarding policing practices in the US, following the murder trial of former police officer Derek Chauvin.