Mohammad Dawood Mommand was at home in Sacramento, California, when he received a call that left him in shock and unable to stand. Ahmad Fawad Yusufi, a cousin who he considered like a brother, had been shot and killed in San Francisco, where he worked as an Uber driver.

Yusufi, 31, was an Afghan immigrant and father of three who came to the US on a special visa after serving as a translator for the US military. Family and gig worker organizers say Yusufi was getting some rest in his car between driving shifts when someone attempted to steal his wallet and shot him to death.

“When my friend said someone killed my brother, I felt someone had broken my legs, broken everything,” said Mommand, who is called Ilays by friends.

Police arrested a 38-year-old man in Oakland on 18 December for the murder of Yusufi last month.

Now Mommand and others are calling for justice, and say the circumstances surrounding Yusufi’s death highlights the tough conditions and long hours that Uber drivers face just to make ends meet.

Like scores of other Afghan Uber drivers, Yusufi would drive for two hours from Sacramento to San Francisco on weekends and work three or four days straight, often sleeping in his car because he couldn’t afford to stay in a room overnight.

In recent years, there have been reports of a growing group of commuters who are forced to travel sometimes more than eight hours away to make a decent living by picking up fares in San Francisco during the day and spending nights in their vehicles.

Mommand is urging Uber to take responsibility for the situation, penning an open letter to top execs including CEO Dara Khosrowshani and issuing a list of three demands from Yusufi’s family. This includes giving the family access to Yusufi’s Uber account, $4m in aid to his family, and better pay for all drivers.

“I will not rest until my brother’s children are taken care of,” Mommand wrote in the letter.

“All I think about is the three kids. Four months, three years, 10 years. They have no father,” he said. “One day my brother’s kids will grow up and they’ll ask me, ‘What did you do for my father? He was killed and what did you do for him?’”

Andrew Hasbun, a spokesperson for Uber, said in a statement: “We’re saddened by the senseless act of violence that took Mr Yusufi’s life. Our hearts go out to his family during this difficult time, and we are grateful to San Francisco police for their quick actions which led to an arrest.”

The ride-sharing company said Yusufi was offline at the time of the murder, and that he took his last trip with Uber on 27 November and logged off the app shortly before 10pm. According to police, the shooting occurred about 5am on 28 November.

Uber said Yusufi’s account has now been unlocked, and that accounts are blocked in situations like this for security and safety reasons.

“No worker should have to sleep in their car to make ends meet,” Cherri Murphy, an organizer with Gig Workers Rising, a San Francisco Bay area organization supporting the family, said.

For years Uber and Lyft drivers have commuted from all around the Bay to work in the city, she added, sleeping in car parking lots wherever they can.

“Ahmad was one of those drivers. Uber knows this is happening.