MONTEBELLO >> Detectives on Tuesday asked for the public’s help in finding a man suspected of fatally shooting his estranged wife during a dispute over the weekend.

Investigators on Monday arrested a 26-year-old woman on suspicion of aiding and abetting the suspect, 26-year-old Christopher Michael Diaz, according to Lt. Julio Calleros. He declined to release the name of the alleged accomplice and how this woman assisted Diaz.

The coroner’s office identified the victim as 28-year-old Roxann Acosta of Alhambra.

Montebello police spokesman Sgt. Marc Marty said Acosta and Diaz were at the apartment of Diaz’s mother in the 1200 block of West Victoria Avenue on Sunday night.

Marty said the couple argued just before 10 p.m. He didn’t know what the argument was about.

“There were witnesses at the scene. They stated he shot the victim and fled the location,” Marty said.

Police received a 911 call reporting gunshots at The Victoria apartment building around 10 p.m. Sunday. Responding officers found Acosta, who died at the scene.

Police consider Diaz, a documented gang member, armed and dangerous. Marty said detectives have not recovered the weapon used in the shooting.

At a vigil at the site of the shooting Monday night, Acosta’s mother, Alicia Acosta, said her daughter had filed for divorce and was eight weeks pregnant with another man’s child.

“She moved on, but he couldn’t move on, so her ex-husband put a gun to her head and shot her,” Alicia Acosta alleged.

Diaz’s mother was at the vigil briefly, but declined to comment.

Roxann Acosta had three children — a daughter and two sons — said her cousin Terra Bernal. The father of the oldest child is serving a life sentence in prison, she said.

“She was a great mother,” Bernal said. “She just made a bad decision to hang out with the wrong person.”

About 100 people attended Monday’s vigil to remember the woman they referred to as Roxy.

Jiji Caballero said she had known Roxann Acosta since middle school. Caballero said her friend was always there for her, including recently when Caballero asked her to visit her father’s grave with her on the second anniversary of his death.

Roxann Acosta had called Caballero on Saturday, but Caballero wasn’t able to answer, she said, so on Sunday, the two exchanged text messages.

“She said, ‘I’ll call you in a little bit,’” Caballero said. “But she didn’t get to call.”

Bernal, four years older than her cousin, said she’ll never forget how happy Roxann Acosta made everyone around her.

“She had the best smile and laugh — and the loudest laughter,” Bernal said. “And she had the kindest heart ever.”

The vigil was set up next to the apartment building’s entrance on Taylor street. Candles, flowers and photos adorned the retaining wall of the building’s decorative rock garden.

Surrounded by her grandchildren and other relatives, Alicia Acosta clutched a black-and-white photo of her daughter and cried into the arms of family members holding her.

“She didn’t deserve this,” she said through tears. “It’s wrong, no matter what, it’s wrong.”

Christopher Diaz has brown eyes, stands 5 feet, 5 inches tall and weighs 145 pounds, Anyone with information on his whereabouts is asked to call 911 or the Montebello police department at 323-887-1313.

EDITOR’S NOTE: This article has been edited to correct the spelling of Roxann Acosta.