After Sacramento police officers shot and killed unarmed man Stephon Clark, they shut off the audio on their body cameras. And it doesn’t look good for the cops, experts and activists say.

Clark, a 22-year-old black man, was in his own backyard Sunday night when two police officers shot at him 20 times, believing him to be holding a gun. He was only holding a phone.

The shooting, which was filmed on two officers’ body cameras and a helicopter camera, is one of the first after a series of Sacramento police reforms requiring the department to release footage of deadly incidents. But it’s not clear whether the transparency will mean justice in Clark’s case.

Sacramento police began pursuing Clark Sunday night, after receiving a 911 call about a man breaking into cars, The Sacramento Bee first reported. Clark has not been confirmed as the subject of the 911 call. In a statement, police said the 911 caller described the suspect as more than six feet tall, but Clark’s grandmother told the Bee her grandson was short. But two police officers starting following Clark, with backup from a police helicopter overhead.

Footage from a heat-detecting camera in the helicopter showed Clark crossing between two backyards. Officers in the helicopter stated he broke a window in the first yard, although the alleged incident is not included in the footage. Then the officers in the helicopter suggested Clark might break into a vehicle.

“He’s running toward the front yard,” an officer in the helicopter said of Clark, who was walking at the time. Then the officer implied Clark might break into a vehicle. “He’s looking into another car,” the officer said.

The officer didn’t know Clark was in his own yard, looking at a car parked there. Clark was staying with his grandparents at the time, and his entrance through the backyard was normal, his grandmother told the Bee. The family home was large, and the doorbell was broken, prompting family members to knock on a back window to be let in, she said.

The helicopter footage showed two police officers approaching the house with their guns drawn. Moments later, they opened fire on Clark, and continued shooting even after he fell to the ground, motionless.

The two officers believed Clark was holding a gun, footage from their body cameras reveals. “Show me your hands,” one shouted at Clark. “Gun, gun, gun!” he shouted almost instantly.

Both officers opened fire, shooting approximately 20 times. They waited approximately five minutes, until other officers arrived, to begin administering medical care.

Kenneth Williams, a criminal-law professor and expert on police use of force at South Texas College of Law, said the officers will have to show to investigators that they reasonably believed Clark was holding a gun.

“It’s not necessarily their subjective beliefs, but the fact of whether it’s reasonable that this man had a gun on him,” Williams told The Daily Beast. Working in the officers’ favor is the fact that it was dark and they might have struggled to see Clark’s hands, he said.

But other factors, like the fact that Clark had been fleeing, and that the officers fired almost immediately after asking to put his hands up, might work against them in an investigation.

“I think they always have an obligation to defuse the situation,” Williams said. “One thing that struck me in the video was that they gave a command and it seemed like they immediately started shooting. The suspect was running away from them.”

Shortly after backup arrived, one officer cut the body camera’s audio. “Hey,” he told an officer who had just arrived on the scene, “mute.”

Activists are questioning why officers chose to cut the audio.

“The frustration the community is feeling is at the lack of compassion and the lack of truth. Why are you now muting the body camera?” Berry Accius, a community activist told The Daily Beast.

“What they’ll say is it’s normal procedure. But we were pushing to make sure body cameras were on police. We want to make sure we see and hear everything. When you’re watching this young man be executed, and you’re wondering if [police] are trying to hide something. They may be, they may not be. But the fact that you see that gives you mixed messages.”

Sacramento police spokesman Sgt. Vance Chandler told the Bee the officers might have been justified in cutting the audio. “There are a variety of reasons why officers have the opportunity to mute their body worn cameras,” he told the paper.

But Williams said the decision was unusual.

“It’s not normal. You would want the camera on,” he said. “You want everything recorded so everything’s public and your supervisors know what’s said. Sometimes they’ll want the camera muted, quite frankly, because they want a story straight. They want their stories to jive. I can’t think of a good reason you’d want to mute the mic.”

Sacramento police reform activists have pushed for greater transparency in the wake of killings by police. In July 2016, Sacramento police shot and killed Jonathan Mann, a mentally ill black man who was armed with a knife, but no gun.

Sacramento officials initially withheld videos of the incident, but later released dashboard camera footage and audio of 911 calls, after pressure from activists. The recordings revealed the officers had attempted to hit Mann with their car before getting out and shooting him.

In response, the city passed reforms requiring police to release footage of all fatal incidents involving police.

Now it’s a question of how those videos will affect the investigation into Clark’s case —and how what police said during those muted minutes.

“I think that’s the largest piece in this,” Accius said. “Police in Sacramento have pushed that we need to trust each other. The black community and other people of color say, ‘well, there’s never been this relationship of trust, so why will there be now?’”