MARTINEZ — A Pinole woman charged with murder Wednesday may have planned to kill herself after fatally shooting her mother Sunday, according to prosecutors.

Police who discovered 62-year-old Claudia Petretti dead at the home she shared with daughter Kimberly Petretti, 43, also found a two-page letter in which the daughter contemplates her and her mother's deaths, deputy district attorney Harold Jewett said.

The women were being evicted and were supposed to leave their home in the 4000 block of Marcas Street at 6 a.m. Sunday. The family's financial troubles may have been motivation for the killing.

"It was a significant event in their lives that may have precipitated this tragic and desperate act," Jewett said.

The evidence points to Claudia Petretti having no knowledge of any killing-suicide plan; she was sitting in an upstairs bedroom watching TV and playing solitaire when she turned her head and Kimberly Petretti shot her in the face with an AR-15 assault rifle, Jewett said.

Police still are investigating the origins of the gun.

Police said they were summoned to the Petretti home at 7:51 a.m. on a disturbance call. They arrived and found Kimberly Petretti sitting on a curb outside, and she directed them to check inside the house.

Whether Kimberly Petretti was considering suicide or planned to go through with it is still being investigated.

"What went through her mind between the time she killed her mother and police's arrival is purely speculative," Jewett said.

Kimberly Petretti was charged Wednesday with murder and an enhancement for use of a firearm. She is scheduled to enter a plea in a Richmond courtroom Jan. 26.

Reach Malaika Fraley at mfraley@bayareanewsgroup.com.