Paroled California convicted killer pleads guilty to child sex abuse material possession

By Tim Fang

A Solano County man who was paroled after being convicted of murder in the 1970s has been convicted of possessing child sexual abuse material, federal prosecutors said.

The U.S. Attorney’s Office for the Eastern District of California said 69-year-old Marvin Mutch of Vallejo pled guilty Friday to the charge, along with the charge of being a felon in possession of ammunition.

Mutch had previously been convicted in 1975 of murdering 13-year-old Cassie Riley, authorities said. According to reports at the time, Riley was assaulted and drowned in Alameda Creek in Union City.

Prosecutors said Mutch served about 40 years in state prison before he was paroled in 2016.

Mutch faced new charges after authorities searched his home in May 2025. Prosecutors said officers located electronic devices which contained “thousands of depictions” of the sexual exploitation of children.

The search also yielded a privately manufactured firearm commonly called a “ghost gun,” eight rounds of ammunition which was found in his vehicle, along with narcotics, prosecutors said.

Mutch faces a maximum penalty of 20 years in prison and a $250,000 fine for the child sexual abuse material conviction and a maximum of 15 years and a $250,000 fine for the conviction on ammunition possession.

Prosecutors said Mutch is scheduled to be sentenced on Aug. 28.