SAN DIEGO (CNS) - A man who fatally stabbed his longtime girlfriend following an argument in their Oak Park home was sentenced Friday to 36 years to life in state prison.
Quang Dang, 37, was convicted in October of second-degree murder in the Aug. 11, 2010, death of 27-year-old Myra Supiping.
Before pronouncing the sentence, Judge Michael Smyth denied a defense motion to reduce the murder conviction to voluntary manslaughter.
Defense attorney Shervin Samimi unsuccessfully argued that Dang killed the woman he considered to be his wife in the heat of passion and under diminished mental capacity.
Since birth, Dang has been diagnosed with "mild mental retardation," his attorney said. The defendant also suffers from psychosis and functions at times like a 6-year-old, Samimi said.
The attorney said Dang has an inability to control his impulses and emotions and got angry when Supiping -- his girlfriend of eight years -- started going out with men she met online, taking their children with her.
"On his best day, he's incapable of controlling his impulses and emotions," Samimi said of his client.
But Deputy District Attorney Patrick Ojeil said Dang went upstairs to retrieve a large kitchen knife and stabbed Supiping at least nine times, mostly in the upper body.
"He (Dang) was acting with reason and judgment the entire time," the prosecutor told the judge.
Smyth noted that Dang attacked his mental health therapist in 1995 and assaulted a man with a baseball bat in 2005.
The judge refused a defense request to strike the assault conviction.
During trial, Ojeil told the jury that Dang stabbed Supiping in bed as she slept with their 2- and 7-year-old sons in the home they shared with his family.
Ojeil said Dang first stabbed the victim in the chest, then Supiping -- who was blind in one eye and partially blind in the other -- rolled onto her side and onto her 2-year-old and was stabbed in the back.
Two months before the murder, Dang and Supiping, both reported to have low IQs, started talking on a "chat line" and Supiping ran up thousands of dollars on her cell phone, which upset Dang, Ojeil told the jury.
A week before she was killed, Dang hit the victim and she went to stay at her mother's house, the prosecutor said.
The day of the murder, the victim's brother dropped her off after an appointment and told the defendant, "Don't touch my sister," the prosecutor told the jury.
About 11 p.m., a relative heard a scream and rushed to the victim's side, according to Ojeil. He said Supiping's last words were "Quang stabbed me."
Ojeil said Dang threw the murder weapon into a rain gutter and retreated to a friend's home, where he was later arrested.
Dang told police that Supiping had cheated on him and he killed her in self-defense when she swung a stick at him, according to Ojeil.