Man Pleads Guilty to Killing His Father

A Simi Valley man has pleaded guilty to the brutal 2024 murder of his father, averting a jury trial and bringing a resolution to a case that underscored the complexities of navigating mental health within the local criminal justice system.

Gerardo Arroyo Almanza officially entered his plea to one count of second-degree murder for the killing of his father, Alfredo Arroyo Sancen. The guilty plea, announced by Ventura County District Attorney Erik Nasarenko, also included three counts of criminal threats against additional family members.

Almanza further admitted to a prior strike offense and a special allegation for personally using a deadly weapon, according to the Vida Newspaper. The case highlights the severe consequences of violent crime in Ventura County and the procedural hurdles courts face when a defendant's mental competency is called into question.

A Wellness Check Turns Deadly

The incident occurred on April 6, 2024, transforming a quiet residential street in Simi Valley into the scene of a fatal family tragedy. Several of Almanza’s family members had driven to his residence to check on his well-being.

As the family members lingered near their parked vehicles across the street from Almanza's home, a sudden and violent confrontation unfolded. Almanza ran out of the residence armed with a knife, directly confronting the relatives and issuing explicit threats to kill them.

The situation escalated rapidly. Almanza chased his mother and father around a parked car in an attempt to harm them. He eventually caught up to his father, pinning him to the ground and stabbing him multiple times.

As neighbors began to gather, drawn by the commotion, Almanza fled the immediate area on foot. An EMT-trained neighbor who witnessed the aftermath stepped in to provide crucial first aid to the wounded Sancen. Despite these efforts, Sancen was transported by emergency medical services to Los Robles Regional Medical Center, where he ultimately succumbed to his injuries. Simi Valley Police Department officers arrived shortly after and arrested Almanza without incident. He was found hiding just a single block away from the crime scene.

Competency Proceedings Delay Justice

Following his arrest, the trajectory of Almanza’s case was heavily altered by questions surrounding his mental health. In the California criminal justice system, defendants must be deemed mentally competent to understand the proceedings against them and assist in their own defense.

Court records indicate that on March 6, 2025, nearly a year after the fatal stabbing, a court-appointed mental health expert determined that Almanza was incompetent to stand trial. This designation typically pauses criminal proceedings and often results in the defendant being transferred to a state hospital for treatment aimed at restoring their competency.

The legal pause was temporary. By October 6, 2025, mental health professionals determined that Almanza’s condition had improved to the point where he was again deemed competent to face the charges. The court proceedings subsequently resumed, ultimately leading to his recent guilty plea and bypassing the need for a preliminary hearing or a jury trial.

Accountability and Community Impact

The resolution of the case was spearheaded by Senior Deputy District Attorney Theresa Pollara, a member of the Ventura County District Attorney’s Office Major Crimes Unit.

In addressing the conclusion of the case, Pollara emphasized the dual nature of the legal outcome. The guilty plea secures definitive accountability for what the prosecutor described as a brutal act of violence against Sancen, as well as the threats of violence levied against other family members. Pollara noted that her primary hope for the surviving family members is that the conclusion of the criminal proceedings allows them to move forward in their healing process.

For residents across the broader 805 region, the plea serves as a stark reminder of the intersection between severe mental health crises and public safety. While this specific incident occurred in Simi Valley, the ripple effects of violent crime and the subsequent legal battles impact countywide resources, from local law enforcement and emergency responders to the specialized mental health divisions within the Superior Court system.

Almanza remains in custody at the Ventura County jail system without bail. He is scheduled to face formal sentencing on September 11, 2026, at 9:00 a.m. in courtroom 12 of the Ventura County Superior Court.

Because of his admission to the prior strike offense and the weapon enhancement, Almanza is facing a substantial prison term. Prosecutors have indicated he will be sentenced to 30 years to life in state prison, plus an additional consecutive term of nine years and four months.