A black man who was killed by a North Carolina state trooper earlier this year was shot in the back and died after massive blood loss, according to an autopsy.

The report by the state medical examiner’s office found that 31-year-old Willard Scott was hit once in the lower back and once in the buttock in the shooting, which happened in Durham in February. He was taken to a hospital but died of the wounds, the report released on Monday said.

The Durham chapter of the National Association for the Advancement of Colored People (NAACP) issued a statement saying that Scott’s family was urging prosecutors to consider charging the trooper.

The shooting happened around 1am on 12 February. Authorities said the trooper, who is white, observed Scott driving erratically and tried to pull him over with his siren and flashing lights.

A highway patrol news release from February said the trooper followed Scott after he failed to stop, and the driver eventually got out of his car and fled on foot.

“During the foot pursuit, an armed confrontation ensued,” the news release said.

Authorities said a handgun that did not belong to law enforcement was found at the scene.

The North Carolina state bureau of investigation (SBI), which is examining the shooting, released a statement in February that said the trooper shot Scott after the chase, but did not elaborate on where Scott was hit. The SBI identified the patrolman as trooper Jerimy Mathis, who was placed on leave.

The autopsy report said Scott was taken to a hospital but died during emergency surgery because of blood loss from the bullet that damaged a major artery and other organs.

The SBI has begun turning over information to the Durham district attorney but has not completed its investigative report, agency spokeswoman Patty McQuillan said on Tuesday. McQuillan said a dashboard camera captured some sound but no video footage of the shooting.

The NAACP described the autopsy as “confirming our worst fears” and said the family was urging a thorough investigation and further training for troopers on de-escalating conflicts.

The statement said the district attorney “must prosecute [Mathis] to the fullest extent of the law, as warranted by the investigation”.