Luis Góngora, the homeless man shot by San Francisco police on 7 April, was killed by a shot to the head from above, lawyers for his family alleged at a press conference as they announced the filing of a claim against the city and county of San Francisco for excessive force and wrongful death.

“This was like a mafia shot,” said Luis Poot Pat, Góngora’s cousin, who attended the press conference on Friday. “I can’t believe in the beautiful city of San Francisco this can happen.”

Attorneys for the Góngora family presented video and photographic evidence that they say shows that police officers shot Góngora from above, while he was either sitting down or lying prone. Photographs from a private autopsy show that Góngora was shot in the top of his head, as well as in the back, both arms, and the abdomen.

“The officer can be seen shooting down at the wounded man, with a handgun in one hand and a shotgun in the other, in a scene reminiscent of a gangster movie,” the claim states. The claim is a precursor to a lawsuit.

The officer can be seen shooting down at the wounded man … in a scene reminiscent of a gangster movie The claim

The lawyers played an enlarged, slow-motion version of surveillance video, previously released by the San Francisco Chronicle, that provides a partial view of the shooting. One of the officers can be seen firing three rounds.

“If you slow down this clip, you will witness that the officer who initially had the shotgun is pointing downward,” said Adante Pointer, one of the attorneys. “Mr Góngora was already down on the ground when this officer decided to pump three shots into his body.”

Pointer also told the Guardian that the absence of stippling or tattooing on Góngora’s body shows that police were more than arm’s-length away from Góngora when they shot him.

“They shot him to pieces,” Pointer said. “It’s ridiculous.”

“Based on multiple eyewitness accounts that are part of our preliminary investigation, Luis Góngora lunged at one of our officers with a large knife,” said Matt Dorsey, spokesman for the San Francisco city attorney’s office. “Góngora posed an immediate and deadly threat, and our officers’ use of lethal force was necessary and legally justified.”

Góngora’s brother and two cousins were present, and his wife, parents, and three children joined the San Francisco press conference via a video call from their home in Teabo, Mexico.

“The measure of a society is how they treat the least among us,” said John Burris, a prominent civil rights attorney whose firm is representing Góngora’s family.

“Luis was treated as if he was the least among us. He was homeless, and the manner in which he was approached and ultimately attacked clearly indicated there was a lack of regard for him as a human being.”

“Today begins our struggle for justice against the unjustified homicide of our son, our father, and our husband,” said Rosana Góngora May, one of Góngora’s daughters, by video phone and through an interpreter.

Family of Luis Góngora at a press conference. Photograph: Julia Carrie Wong/The Guardian

“Despite his moments of poverty, he never lost contact with us here in Yucatan and we always dreamt of coming back together and meeting in Yucatan … We will fight as a family to raise his name and expose the shameful conduct of the police.”

Góngora was shot and killed in San Francisco’s Mission district, near a homeless encampment where he lived in a tent. The fatal encounter began when two homeless outreach workers observed Góngora carrying a large knife and called 911, according to police.

Eyewitness and police accounts diverge widely over what happened once police arrived on the scene.

Police officials have claimed that after two officers fired less-lethal beanbag rounds at Góngora, he stood up and “charged” at the responding officers with the knife, prompting them to open fire.

The manner in which he was approached and ultimately attacked indicated there was a lack of regard for him as a human John Burris, civil rights attorney

But six eyewitnesses – including other residents of the homeless encampment, neighbors who live in apartments across the street, and a pedestrian who was walking on the sidewalk – have challenged that narrative.

“He didn’t get up until they were shooting,” Smith Patrick, a neighbor who had an unobstructed view of the shooting from her second-story window, told the Guardian the day after the shooting. “I would by no stretch of the imagination say that he was charging them. His body was recoiling from bullets.”

Surveillance video revealed that the officers began shooting just 30 seconds after the officers exited their cars. The footage does not show the shooting itself but provides a view of the police officers’ arrival and audio of the encounter.

Burris also called on San Francisco’s district attorney to file criminal charges for murder against the two police officers.

“There is no excuse for what happened,” Burris said. “It was done in large measure I believe because of the condition in which he lived, and these officers used deadly force because they could, not knowing that people would care.”

