A San Rafael woman who stabbed her mother to death last year is not guilty by reason of insanity , a Marin County jury determined Monday.

Tonantzyn Oris Beltran, 30, was charged with murder for the death of Olivia Beltra n, 55, in January 2024. The jury heard testimony for four weeks and deliberated for three hours before reaching its verdict Monday afternoon.

The verdict means the jury found that mental illness made the defendant incapable of knowing the attack was wrong.

Marin County Superior Court Judge Geoffrey Howard will have the defendant placed in a psychiatric facility. Her defense attorney, Matthew Siroka, said she will be held indefinitely.

Beltran would have faced 25 years to life in prison if convicted of murder, Siroka said. He praised the jury after the verdict.

“I t

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