Simi Valley Man Sentenced to Over 39 Years to Life in Prison for Fatal Knife Attack on His Father

VENTURA, Calif. — A Simi Valley man has been sentenced to serve nearly four decades to life behind bars for stabbing his father to death and terrorizing his family with a knife during a welfare check, county prosecutors announced.

Click here to view the official Ventura County District Attorney's Office press release regarding the sentencing of Gerardo Arroyo Almanza.

The state prison sentence was announced by Ventura County District Attorney Erik Nasarenko following a formal sentencing hearing in Ventura County Superior Court.

Authorities identified the defendant as 37-year-old Gerardo Arroyo Almanza (born April 23, 1989), a resident of Simi Valley.

Almanza appeared before a Superior Court judge to receive his sentence under case number 2024009178. The court ordered Almanza to serve 39 years and 4 months to life in California state prison following his August 3, 2026, guilty plea to second-degree murder and three counts of criminal threats.

Violent Street Confrontation, Fatal Stabbing, and Neighbor Intervention

According to official court filings and prosecution summaries released by the District Attorney's Office, the fatal incident occurred on the afternoon of April 6, 2024, outside Almanza's home in Simi Valley.

Concerned about his mental state, several of Almanza's family members drove to his residence to perform an informal welfare check. As family members stood near their parked vehicles across the street, Almanza charged out of his house armed with a large knife and began screaming threats to kill them.

Almanza aggressively chased his mother and father around a parked automobile. After catching up to his father, Alfredo Arroyo Sancen, Almanza tackled him, pinned him to the ground, and repeatedly stabbed him in the torso.

As horrified neighbors began shouting and gathering in the street, Almanza fled the scene on foot.

An off-duty EMT neighbor rushed to the scene and administered immediate CPR and first aid to Sancen before emergency medical services arrived. Sancen was transported via ambulance to Los Robles Regional Medical Center in Thousand Oaks, where he succumbed to his injuries.

Responding patrol officers from the Simi Valley Police Department secured the neighborhood and located Almanza hiding inside a residential block roughly one street away from the crime scene, placing him under arrest without further incident.

Competency Restoration and Emotional Family Victim Statements

Following his 2024 arrest, criminal proceedings were temporarily suspended on March 6, 2025, after a court-appointed mental health expert determined Almanza was incompetent to stand trial. Following medical treatment, the court declared Almanza's competency restored on October 6, 2025, clearing the way for criminal prosecution.

During the September 2026 sentencing hearing, surviving family members delivered emotional victim impact statements detailing the devastating generational trauma caused by the attack.

Jose Iglesias-Arroyo spoke directly to the court regarding the profound loss of his grandfather:

"To me this is not just a case or a headline, this is my grandfather, this is my family," Iglesias-Arroyo shared inside the courtroom.

The prosecution was led by Senior Deputy District Attorney Theresa Pollara of the District Attorney’s Office Major Crimes Unit.

"On April 6, 2024, several of Almanza’s family members drove to his residence in Simi Valley to check on his well-being... Almanza ran out of the house, confronted his family members with a knife and threatened to kill them. Almanza chased his mother and father around a parked car. After catching his father and pinning him to the ground, Almanza stabbed him several times," the District Attorney's Office detailed in its official media release.

Formal Charges, Prior Strike Allegations, and Prison Commitment

Almanza pled guilty and was sentenced on the following formal counts under the California Penal Code:

• PC 187(a): Second-Degree Murder (Felony)
• Three Counts of PC 422: Criminal Threats Against Family Members (Felony)

Additionally, Almanza formally admitted to special sentencing enhancements and prior criminal record allegations, including:

• PC 12022(b)(1): Personal Use of a Deadly Weapon (Knife)
• PC 667(e)(2)(A): Two Strikes Sentencing Enhancement
• PC 667S2FP: Strike 2 Foreign Prior Conviction

Almanza will remain incarcerated at the Ventura County Pre-Trial Detention Facility until California Department of Corrections and Rehabilitation (CDCR) officials transfer him to a state prison facility to begin serving his sentence. Official court press advisories can be accessed on the Ventura County District Attorney's Office Newsroom.

Sources

• Ventura County District Attorney's Office Official Press Release (Release No. 26-126)