Sequita Thompson, center, discusses the shooting of her grandson, Stephon Clark, during a news conference on Monday in Sacramento. (AP Photo/Rich Pedroncelli)

During an emotional news conference Monday, Stephon Clark’s family and civil rights leaders demanded that Sacramento police be held accountable for the 23-year-old father’s death, calling for charges against the officers involved and changes to local police department policies.

Family attorney Ben Crump called for an independent autopsy for Clark as a “solemn obligation.”

During the news conference at Sacramento City Hall, Clark’s grandmother, Sequita Thompson, fought back tears as she recounted the night Clark was killed. Clark was shot in her backyard after two police officers approached him for allegedly breaking into cars that night. The police department said the officers believed he was armed, but Clark was holding a cellphone.

“When a young man who was bombing homes in Austin, Texas, the police followed him for hours, he wasn’t shot once,” Crump said. “But an unarmed black man holding a cellphone is shot 20 times.”

Clark’s brother, Stevante Clark, erupted in an emotional chant of his brother’s name. “Say it louder!” he repeated as he roused tearful attendees.

Sacramento NAACP President Betty Williams was among several speakers who called for full transparency in the investigation and for charges to be filed against the two officers who shot and killed Clark.

“We want to make sure that if there is something different, we need to see it,” Williams said.

Williams later said it was a “lack of trust” that drove the Clark family and Crump to call for their own autopsy.

“We know that local prosecutors investigating local police is a conflict of interest,” said the Rev. Shane Harris of National Action Network. “And we must get independent investigations on state and federal levels, because we know that a prosecutor investigating police officers that endorse them is like a student grading their own paper.”

Williams said she met with Sacramento Police Chief Daniel Hahn and challenged him to be the model police chief for other cities.

“He signed up for this,” Williams said. “At the end of the day, we also understand that he inherited the culture of this police department.”

Williams and the NAACP announced that they are asking the police department to change its policies for turning off the body-cam audio and foot-pursuit protocol. Williams said Hahn is open to considering the foot-pursuit policy used in Oakland, Calif., which provides police with other options — including K-9 pursuit, Taser and surveillance until backup arrives — before resorting to firing their weapon.

Leaders praised the Sacramento Police Department for releasing the body-cam footage less than 72 hours after the incident.

“That puts Sacramento on the map just by itself,” Williams said, noting that it is rare for police departments to release video so soon.

Sacramento Sheriff Scott Jones released the audio at Hahn’s request.

“That’s the kind of transparency we are looking for,” said Alice Huffman, president of the California NAACP.

Crump previously represented the families of Michael Brown, Trayvon Martin and Tamir Rice.

Clark’s funeral is scheduled for Thursday. The Rev. Al Sharpton will give the eulogy.

“You can see by this community, they are not going to let this go,” Huffman said.