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District Attorney

Posted on: November 2, 2022

Parole Denied for Murderer Cheyenne Knox

Sonora, California – Tuolumne County District Attorney Cassandra Jenecke announced today that on September 13, 2022, 52-year-old Cheyenne Knox was denied release at a parole hearing held via videoconference.  This was Knox’s fifth subsequent parole hearing and his sixth denial of parole.    

On July 17, 1988, Knox shot Yvette Stagno in the back of the head with a .28 caliber double barrel shotgun on Green Springs Road.  He was 17 years old at the time and she was 19.  They had argued after she had told him that she did not want to get back together with him in a romantic relationship.  He shoved her to the ground and as she was trying to get up, he shot her twice at close range.  

After murdering her, he put Yvette’s body in the back of her car and drove the car to her parent’s home in Sonora.  He entered the home through a window and took a blanket off Yvette’s bed and a garage door opener from the home. The garage door opener was routinely used by Yvette to enter the home and he wanted to make it look as if she was just missing.

Knox then wrapped Yvette in the blanket from her home and drove her to the Delta Mendota Canal in Alameda County where he dumped her body. He then drove Yvette’s car back to Sonora and parked it at the Sonora Community Hospital.   Over the next several weeks he contacted the victim’s family numerous times to ask if they had seen her, if he could help search for her, or even to offer possible sightings and theories as to what had happened to her.  

On July 26, 1988, Knox flew to Pennsylvania to his father’s residence.  On July 30, 1988, Yvette’s car was located at the hospital parking lot.    The car was opened and the driver’s seat was moved all the way back.  Blood was located on the rear bumper, on the trunk, and running down the rear tire well. Analysis confirmed the blood matched Yvette’s blood type. On August 2, 1988, a body was found on the Delta Mendota Canal but it took until August 20, 1988 to identify the body as Yvette’s through dental records.   

Investigators from Tuolumne County Sheriff’s Office flew to Pennsylvania on August 16, 1988 to speak to Knox.  Knox initially denied any involvement in Yvette’s death, but later admitted killing her. He told investigators that his dog Blackmore instructed him on how to kill Yvette. He has now admitted during his parole hearings that the story about his dog was a lie concocted by him and his lawyer to try to avoid being found guilty. Knox was eventually found to be sane and was tried as an adult in Tuolumne County Superior Court. Prior to a trial, he pled guilty to first degree murder and received a 25-year-to-life sentence.   

Yvette’s mother and father, her sister, and her brother attended the hearing via videoconference with District Attorney Cassandra Jenecke.  

The hearing lasted nearly four hours. District Attorney Cassandra Jenecke argued that Knox still poses an unreasonable risk of danger to the community and is a threat to public safety based on his criminal mindset, incarceration disciplinary history, and psychiatric reports that rated him at a moderate risk of violence reoffending. She further argued that the murder of Yvette was done in cold blood with zero provocation in a particularly heinous and pre-meditated way.  The victim’s family gave very powerful impact statements to the Board emphasizing the devastation that this crime has inflicted on their lives. Sylvia Stagno, mother of Yvette, as part of her statement addressed the commissioners and stated that:

“Yvette’s dad and I believe Cheyenne gave her a death sentence without parole.  He gave her family a life sentence without her.   He should remain with his sentence in prison just like we have to do our time.  He should not get out until Yvette can come home.”  

Commissioners deliberated for approximately thirty minutes and found Knox was not suitable for parole based on his continued risk to society.  The Commissioners denied Knox another parole hearing for an additional three years. While Knox had previously received a three-year denial of parole on January 26, 2021, he successfully petitioned for his case to be advanced again, for the third time. This advancement was a devastating occurrence for Yvette’s family and is each time it happens. Unfortunately, with a three-year denial, the Board of Parole Hearings will automatically review Knox’s case after a year to determine if his case should be advanced, which means that Yvette’s family and our Office may have to appear in about 18 months to again argue against this murder’s release. District Attorney Jenecke states, “We will be at every hearing to support Yvette’s family and fight against Knox’s release.”  

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