A 72-year-old woman was convicted Thursday of first-degree murder for fatally shooting her 96-year-old mother in the Southern California home they shared.

Gretchen DeStefano was sitting in a recliner on Aug. 28, 2014 talking on the phone with a relative when her daughter, Christine Reynolds, retrieved a 9 mm handgun from her car and shot her mother in the head.

The two had bickered for years, and Reynolds was angry with her mother, attorneys said.

Deputy Public Defender Adam Vining argued that Reynolds, who had been drinking vodka and taking antidepressants, was too drunk to know what she was doing and the shooting was an accident.

Reynolds, however, didn't say that when she called a 911 dispatcher or to her 62-year-old brother who ran into the room and found her standing near their mother's body with a gun in her hand.

"She looks at him and says 'I killed the b----,'" Deputy District Attorney Keith Burke told jurors. "She didn't say she was sorry. She didn't say it was an accident. Didn't express any remorse that he could see."

Reynolds testified that she bought the gun four years ago because she intended to kill herself, Burke said.

Reynolds told a sheriff's deputy that her mother regularly told her she was a horrible person.

Jurors in Orange County Superior Court deliberated for only a few hours before returning the verdict.

Reynolds faces up to life in prison when sentenced Dec. 18.