Wesley Shermantine, one half of the notorious duo known as the “Speed Freak Killers,” has died while serving a death sentence in California. Shermantine, 60, was pronounced dead on September 17 at California State Prison, Sacramento, where he had been held for more than two decades. Officials said the county coroner will determine the cause of death.
Shermantine Was Linked to a String of California Murders
Shermantine and his childhood friend Loren Herzog became associated with a series of murders and disappearances across California’s Central Valley, particularly in San Joaquin County, from the mid-1980s through the late 1990s.
Investigators believed the pair could have been responsible for numerous killings during a prolonged period of drug-fueled violence. The exact number of victims has never been conclusively established.
Shermantine was convicted in connection with four murders. His convictions included the 1998 killing of 25-year-old Cyndi Vanderheiden, the disappearance and death of 16-year-old Chevelle “Chevy” Wheeler in 1985, and the 1984 killings of Paul Cavanaugh and Howard King.
He received a death sentence in 2001 and was initially placed on California’s Death Row. He was later transferred from San Quentin State Prison to California State Prison, Sacramento, following the state’s suspension of executions.
The Case of the Speed Freak Killers
The investigation into Shermantine and Herzog became one of California’s most closely followed serial-killing cases. Authorities connected the two men to multiple disappearances, although questions remained about the full extent of their alleged crimes.
Herzog was also convicted in connection with several killings, but an appeals court later overturned his murder convictions after determining that his confessions had been coerced. He eventually pleaded guilty to voluntary manslaughter and was released on parole in 2010.
Herzog was required to live under strict supervision at a trailer on the grounds of High Desert State Prison near Susanville. He died by suicide in 2012 at age 46.
Shermantine remained incarcerated and continued to serve his death sentence.
Death Brings New Chapter to Long-Running Case
Shermantine’s death closes another chapter in a case that left numerous families searching for answers for decades. His death was confirmed at approximately 6 p.m. on September 17 at the prison’s health center.
The official cause of death has not yet been released and is expected to be determined by the Sacramento County Coroner’s Office.
For relatives of victims, the case has remained tied not only to the convictions but also to years of uncertainty surrounding people who disappeared during the period when Shermantine and Herzog operated in California’s Central Valley.
Cyndi Vanderheiden’s father, John Vanderheiden, previously spoke about his daughter’s disappearance and the impact it had on the family, remembering her as someone who brought happiness to their home.
Shermantine’s death comes years after the crimes that made the “Speed Freak Killers” one of California’s most notorious criminal cases.
