BAKERSFIELD, Calif. -- The penalty phase of the Vincent Brothers murder trial got under way Monday morning with the ex-girlfriend and mother of Brothers' only surviving child taking the stand.

Shann Kern testified that Brothers assaulted her after an argument in May 1988, ABC23 reported.

She said Brothers had not returned to the couple's apartment for three days.

Kern said when he did return she asked if Brothers could give her ride to Lancaster for a family reunion.

"He said, 'I'm not taking you f-ing anywhere,'" Kern testified. She said she then threw her house slipper at him striking him in the shoulder.

"He came across the bed and beat me in the face," said Kern.

She said he beat her six or seven times.

Kern testified the beating left her face black and blue with split lip and swollen eye.

She called 911 after the beating and was taken to Kern Medical Center for treatment.

Kern was pregnant at the time with their child.

Brothers was charged with a misdemeanor that was later expunged from he record.

Last week the defense called the incident minor.

Kern said that after the domestic violence incident she moved out, living for a time at a home for battered women and a home for unwed mothers.

She said she maintained a relationship with Brothers for the sake of their daughter Margaret Kern-Brothers.

Last Tuesday the jury found Brothers guilty of murdering his wife Joanie; the couple three children; Marques, Lyndsey, and Marshall, and mother-in-law; Ernestine Harper.

The same jury will determine if Brothers will receive the death penalty or life in prison.