Update: Police have arrested Jesus Ramirez, a 48-year-old San Francisco resident, in connection with Camacho’s murder.

A 59-year-old homeless man died after he was stabbed with a knife by two men estimated to be between the ages of 30 and 50, police say. The incident took place near 25th Street and Potrero Avenue around 8 p.m. Thursday. It is San Francisco’s first homicide of 2018.

According to three witnesses, the victim succumbed to a stab wound to his throat before paramedics arrived on the scene and transported him to the hospital.

The San Francisco Medical Examiner identified the man as Mark Camacho, 59, of San Francisco. Ricky Camacho, 61, who identified himself as the victim’s brother, said Mark was born and raised in the Mission District.

Residents say Camacho was a familiar and well-liked face who spent time in front of the doorstep where he was murdered.

One witness, a 25-year-old woman who asked to remain anonymous, saw the murder take place. She said she looked out of her window overlooking 25th Street when she heard one man, about 30 years old, in a loud argument with Camacho.

The suspect, dressed in “nice” blue jeans and a black sweater, punched Camacho unconscious, then fled, she said.

The witness said that was when the second suspect, who she described as a 60-year-old man with gray hair, approached Camacho on the ground, put him in a chokehold, slashed his throat and stabbed him multiple times.

The witness recognized the second man as a homeless person who often slept near the corner of 25th Street and Potrero. At first, she yelled for the man to “help him,” then she screamed, “stop him, he’s stabbing him!”

The witness said the older suspect “walked off with his cart, like normal.”

She said she followed him toward the James Rolph Jr. Playground. She said she asked the suspect why he stabbed Camacho. He responded, “he owed me one.”

She said the police asked her to identify a suspect last night, “but it wasn’t him.”

“I’m still traumatized. I haven’t been able to sleep,” the witness said. “My daughter keeps asking me if he’s dead, and I don’t know what to tell her.”

The witness remembers Camacho as respectful, and that “he gave me food before.”

The murder took place in front of the house of Lou, 81, who wasn’t home at the time of the murder. Lou said Camacho would sit on his step, drink a beer and eat food.

Lou said Camacho was “polite” to him and “would pick up his own garbage.”

Richard Segovia, 64, who lives on the block where the murder took place, said he’s known Camacho since the 1960s.

“He gave me a Christmas present,” Segovia said.

Segovia had talked to Camacho shortly before he was stabbed. Camacho had fist-bumped with Segovia and asked if he was doing well.

About 20 minutes later, Segovia heard police sirens and then went to check on what was happening.

He said Camacho was already dead before paramedics tried to give him oxygen. Segovia estimated there were about three quarts of blood around his body from the throat wound.

Segovia said he and another man on the scene began to pray and said, “come on, warrior, you’re going to be OK.”

Segovia said he doesn’t know why someone would have murdered Camacho. He said the suspects didn’t take Camacho’s duffel bag, which police took as evidence.

This morning, Segovia created an altar where Camacho was murdered.

Ricky, the victim’s older brother, showed up at the altar this morning to put up red, white and blue tissue paper, representing Camacho’s Puerto Rican heritage.

“He’s lived a life on the edge,” Camacho said of his brother. He said Mark had been homeless for at least a decade and was receiving a government disability check.

Ricky said his brother was “in and out of SROs [Single Room Occupancy’s],” and was kicked out of navigation centers.

Ricky, who lives in South San Francisco, drives a taxi in the city and would often pass by his brother living on the street. He said he only recently reconnected with his brother and was doing his best to help him.

“It’s just sad for me, because I loved my brother and couldn’t do anything for him because he didn’t embrace the help,” he said.

Ricky said he recently got angry with his brother and told him “not to get any closer to [him].”

“I realized that that wasn’t the right thing to do, so we made up — we hugged and kissed,” he said.

Camacho said his brother left him a voicemail last night at 7:30 p.m. asking to meet up on Saturday and grab a beer. “Had I known, I would have picked up,” he said.

Ricky said he remembers when the two were boys growing up in the Mission and members of the “Mission Boys Branch, back when it was all boys.” He said Mark played football and was on the “80s” basketball team.

The victim’s friends had come to leave candles, flowers and pictures of Mark. The woman who witnessed the stabbing left a candle, too, because she said, “he didn’t deserve it.”