The family of an African American man killed by a white officer has issued an emotional plea for “drastic change” in policing and for the shooter to be prosecuted.

Rayshard Brooks died on the weekend after a police officer shot him twice in the back, the latest killing to fuel nationwide outrage against police brutality and racial injustice.

“How many protests will it take to ensure that the next victim isn’t your cousin, your brother, your uncle, your nephew, your friend, or your companion so that we can finally end the suffering of police excessive force?” his cousin, Tiara Brooks, told a press conference on Tuesday morning (Australian time).

Mr Brooks’ daughters Blessen, 8, left, and her sister, Memory at a family news conference. Photo: AAP

The Fulton County Medical Examiner’s office ruled Mr Brooks’ death a homicide.

“We’re tired and we are frustrated. Most importantly we’re heartbroken, so we need justice for Rayshard Brooks,” Ms Brooks said.

“The trust that we have in the police force is broken. The only way to heal some of these wounds is through a conviction and a drastic change in the police department.”

Mr Brooks’ wife, Tomika Miller, spoke about the pain of her husband’s death and implored the public to protest peacefully in his name.

“I can never get my husband back,” she said.

“I can never get my best friend. I can never tell my daughter, ‘Oh, he’s coming to take you skating or swimming lessons.’ So it’s just going to be a long time before I heal. It’s going to be a long time before this family heals.”

Tomika Miller, the wife of Rayshard Brooks, holds their daughter Memory, 2, during the family press conference. Photo: AAP

Several other relatives attended the news conference in tears and spoke of a warm family man who loved to take his daughter skating.

One man left the room during the briefing in hysterics, shouting “Somebody took my cousin!”.

Mr Brooks’ fatal encounter with the police came after officers responded to a call that he had fallen asleep in his car in a Wendy’s restaurant drive-through lane.

Caught on video, the encounter seemed friendly at first but when an officer moved to arrest him, Mr Brooks struggled with him and another officer at the scene before breaking away across the parking lot with what appeared to be a police Taser in his hand.

The crime scene at a Wendy’s restaurant carpark in Atlanta. Photo: AAP

A video from the restaurant’s cameras shows Mr Brooks turning as he runs and possibly aiming the Taser at the pursuing officers, both white, before one of them fires his gun and Brooks falls.

Lawyer for Mr Brooks’ family Chris Stewart said the police should have let Mr Brooks walk home rather than pursuing and shooting him.

“It didn’t have to go to that level,” he said. “Where is the empathy in just letting him walk home?”

Atlanta’s police chief Erika Shields resigned over the shooting. The officer suspected of killing Brooks was fired, and the other officer involved in the incident was put on administrative leave.

Prosecutors will decide by midweek whether to bring charges, Fulton County District Attorney Paul Howard said on Sunday.

The death of Mr Brooks, and the separate shooting of a black jogger, Ahmaud Arbery, near the coastal town of Brunswick in February involving a former law enforcement officer, has driven calls for racial justice in Georgia.

Atlanta Mayor Keisha Bottoms announced immediate reforms within the police department, including orders requiring police officers to de-escalate situations and requiring officers to intervene when they see a colleague using excessive force.

Ms Bottoms told a media briefing that she was heartbroken and angry over Brooks’ death and she could not wait for an advisory council to come up with police reform recommendations.

President Donald Trump told reporters the shooting in Atlanta was “a terrible situation” and “very disturbing”.

Mr Brooks’ death reignited protests in Atlanta after days of worldwide demonstrations against racism and police brutality prompted by the death of George Floyd, who was killed when a Minneapolis policeman knelt on his neck for nearly nine minutes on May 25.

-with AAP