Paroled Murderer Pleads Guilty to Possessing Child Sexual Abuse Material and Being a Felon in Possession of Ammunition

SACRAMENTO, Calif. - Marvin Mutch, 69, of Vallejo, pleaded guilty today to one count of possession of child sexual abuse material (CSAM) and one count of being a felon in possession of ammunition, U.S. Attorney Eric Grant announced.

According to court documents, in May 2025, law enforcement officers executed a search warrant at Mutch's residence. Inside his residential office, officers seized various electronic devices containing tens of thousands of depictions of the sexual exploitation of children. Some of these images included depictions of the sexual abuse of children as young as 3 or 4 years old. Officers also seized a privately manufactured "ghost gun" containing eight rounds of ammunition from the center console of Mutch's vehicle parked in the garage.

Mutch is prohibited from possessing ammunition because he is a felon who was convicted in 1975 of murdering a 13-year-old girl. Press reports issued shortly after Riley's murder indicated that her killer beat her and then drowned her in Alameda Creek in Union City, California. Mutch served approximately 40 years in the California state penal system for this crime before being paroled in 2016.

The Solano County Sheriff's Office is conducting the investigation with assistance from the FBI Violent Crime Task Force and the Solano County District Attorney's Office. Assistant U.S. Attorneys Adrian T. Kinsella and Sam Stefanki are prosecuting the case.

Mutch is scheduled to be sentenced by U.S. District Judge Dena Coggins on Aug. 28, 2026. Mutch faces a maximum statutory penalty of 20 years in prison and a $250,000 fine on his CSAM conviction and a maximum statutory penalty of 15 years in prison and a $250,000 fine on his felon in possession of ammunition conviction. The actual sentence, however, will be determined at the discretion of the court after consideration of any applicable statutory factors and the federal Sentencing Guidelines, which take into account a number of variables.

This case is part of Operation Take Back America, a nationwide initiative that marshals the full resources of the Department of Justice to repel the invasion of illegal immigration, achieve the total elimination of cartels and transnational criminal organizations, and protect our communities from the perpetrators of violent crime.

This case was also brought as part of Project Safe Childhood, a nationwide initiative launched in May 2006 by the Department of Justice to combat the growing epidemic of child sexual exploitation and abuse. Led by the United States Attorneys' Offices and the Criminal Division's Child Exploitation and Obscenity Section, Project Safe Childhood marshals federal, state, and local resources to locate, apprehend, and prosecute those who sexually exploit children, and to identify and rescue victims. For more information about Project Safe Childhood, please visit www.usdoj.gov/psc. Click on the "resources" tab for information about internet-safety education.