The family of Stephon Clark joined hundreds at a rally urging California’s capital city not to let his memory or calls for police reform fade nearly two weeks after the 22-year-old unarmed black man was killed by police in Sacramento.

Mr Clark’s fiancee, Salena Manni, stood on stage with his two young sons, grandmother and uncle for the gathering organised by Sacramento native and former NBA player Matt Barnes, who pledged to create a scholarship fund for the children of black men killed by police.

“All he wanted to do was go see his sons again, and unfortunately he can’t,” Curtis Gordon, Clark’s uncle, said as he recalled seeing his nephew hours before the shooting.

“So remember that — while we mourn, while we shout, while we cry — because it ain’t just our pain, it’s their pain.”

Mr Barnes amplified calls for charges against the two officers who are on administrative leave.

“It’s more than colour — it comes down to right and wrong,” he said. “You’re trying to tell me I can kill someone and get a paid vacation?”

The peaceful demonstration that drew between 200 and 300 people to a city park came a day after a private autopsy released by the family showed Mr Clark was shot from behind.

Mr Clark was killed March 18 by two police officers responding to a call of someone breaking into car windows.

They yelled that he had a gun before shooting, but it was only a mobile phone.

The police department says it has not received an official autopsy report from the county coroner’s office.

Activists and faith leaders called for justice not just for Mr Clark, but for all black men killed by police.

Family members of Joseph Mann, who was killed by Sacramento police in 2016, also spoke. The chairman of a police oversight commission urged attendees to continue their activism by showing up to meetings and pushing for systemic change.

“This little small town can show this nation our great big heart,” the Reverend Kevin Ross said.

The night before, several hundred protesters marched through downtown streets for nearly four hours, with Black Lives Matter Sacramento leaders diffusing tensions on several occasions to keep the march peaceful.

The release of the private autopsy commissioned by Mr Clark’s family on Friday has prompted fresh outrage.

Pathologist Doctor Bennet Omalu, known for his study of a degenerative brain condition in football players, announced that Mr Clark was hit by eight bullets — six in the back, one in the neck and one in the thigh — and took three to 10 minutes to die. Police waited about five minutes before rendering medical aid.

Dr Omalu said the proposition that Mr Clark was assailing the officers, meaning he was facing them, is “inconsistent with the prevailing forensic evidence”.

Police video of the shooting does not clearly capture all that happened after Mr Clark ran into his grandmother’s back yard.

Mr Clark initially moved toward the officers, who were peeking out from behind a corner of the house, but it is unclear if he was facing them or knew they were there when they opened fire after shouting “gun, gun, gun”.

After 20 shots, officers called to him, apparently believing he might still be alive and armed. They eventually approached and found no gun, just a mobile phone.

Governor Jerry Brown, a Democrat, called Mr Clark’s death tragic and said it “raises a number of very serious questions”.