A convicted killer was attacked in a California courtroom during his sentencing for stabbing his girlfriend to death nearly four years ago, authorities said this week.

Euren Balbuena, 33, was sentenced to 33 years to life in prison for killing his girlfriend, 31-year-old Zaira Patino-Trejo, Ventura County District Attorney Erik Nasarenko announced in a Thursday news release. During the proceedings, a "brief altercation" unfolded as victim impact statements were being read in court, the DA said.

The victim's mother, who was also stabbed twice during the attack, was reading her impact statement when her husband, the victim's stepfather, lunged at Balbuena, the Ventura County Star reported, citing a spokesman for the DA's Office. He landed at least one punch before the two men were separated by bailiffs, the spokesman told the outlet.

Balbuena was convicted by a jury on November 21, 2023, of the first-degree murder of Patino-Trejo, battery causing great bodily injury, and assault with a deadly weapon against her mother, the DA said.

Authorities say Balbuena and Patino-Trejo, who had a "history of domestic violence in the relationship," were arguing in their Simi Valley apartment on Feb. 27, 2020.

Unable to contact her daughter, Patino-Trejo's mother, Ariadna Avetisyan, went to the couple's home and saw "signs of more abuse on her daughter's face," the DA's office said.

Balbuena would not let Patino-Trejo out of the apartment and grabbed a kitchen knife, stabbing Avetisyan twice in the head before attacking her daughter, authorities said. Balbuena then stabbed Patino-Trejo more than 30 times with multiple knives, killing her.

The victim's mother ran bleeding from the apartment and contacted a bystander who called 911, the DA said. Police responded to the scene and arrested Balbuena. Three days after the attack, he was charged with the murder of Patino-Trejo.

Patino-Trejo worked as a client associate for Merrill Lynch Wealth Management, the Simi Valley Acorn reported.

"Zaira Patino-Trejo was such a vibrant young woman with a bright future," Supervising Senior Deputy District Attorney Melissa Suttner said in a statement Thursday. "We cannot replace her unimaginable loss, but we pursued justice for Zaira and her family. We hope that this sentence brings some small relief to her family, knowing that Euren Balbuena was held accountable for her brutal murder." 

In:
• California
• Murder

Stephen Smith

Stephen Smith is a senior editor for CBSNews.com.