California woman who thought victim was ‘the devil’ pleads insanity

A California woman who pleaded insanity for stabbing a Pullman couple in 2023 under direction of “God’s will” will be committed to a psychiatric hospital.

Whitman County Judge Roger Sandberg denied 31-year-old Tiffany Dennison’s petition for conditional release Thursday afternoon in Whitman County Superior Court in Colfax. The case was heard following Court Commissioner Douglas Robinson’s acceptance of a mental health defense in November.

Dennison was arrested by Pullman police officers in September 2023 and has remained in the Whitman County Jail.

Court documents show two people were hospitalized after Dennison attacked them with a knife. She was charged with attempted second-degree murder, first-degree assault with a deadly weapon and possessing weapons capable of producing bodily harm.

The man suffered a punctured lung and stab wounds that hospital staff informed officers narrowly missed major arteries, according to court documents. The woman was treated for gashes as well.

Officers were informed there was a toddler at the residence. Dennison told police she stabbed the man because she believed he was “the devil,” and could not let the child be raised by him.

In court, psychologists Nathan Henry and Gregory Wilson said they believed Dennison had suffered from brief psychosis during the incident.

Both psychologists said it was the first time Dennison had experienced a psychotic episode, and they were unable to determine if she will undergo another in her life.

Henry noted the majority of psychotic breaks are nonviolent, and her actions were abnormal.

Jail staff testified in court Dennison had been a “model inmate” during her stay in jail, who never got into physical or verbal altercations and tolerated problematic inmates. Wilson said Dennison had written a self-help book for people to cope with first arriving in prison.

Wilson testified she didn’t pose a safety risk because she had no mental health issues or history of violence while in jail. Henry, on the other hand, determined she was a threat to public safety.

Sandberg ruled that Dennison is a substantial danger to the public and should not be released. He used Dennison’s past mental health records in his decision, who said she had long struggled with determining reality.

Dennison will be admitted to Eastern State Hospital in Medical Lake, Wash. She will receive mental health treatment from doctors, who will determine if she can be released. Dennison can petition for release every six months.

Pearce can be reached at epearce@dnews.com.