Wesley Howard Shermantine Jr. was born on February 24, 1966, in Linden, California. He grew up in a small town with less than 2,000 residents, where he lived on the same street as his friend, Loren Herzog. Their friendship was strong because there were not many other children around to play with. Shermantine's father was a successful contractor and real estate developer, and he often spoiled Wesley with gifts and money.

As children, Wes and Loren enjoyed spending time outdoors. They loved hunting and fishing in the countryside of San Joaquin County. Both boys graduated from Linden High School in 1984. While in school, they did not have many friends and were known for their bad behavior. They often bullied others and engaged in drinking and drug use, particularly methamphetamine.

During their early adulthood, Shermantine and Herzog were known to visit the Linden Inn bar, which was owned by the father of a woman named Kim Vanderheiden. At this time, Herzog had a brief affair with Kim. The residents of Linden were aware of the duo's reputation for using drugs and were familiar with their activities at the bar.

Wesley Howard Shermantine Jr. was involved in several murders alongside another man, Loren Herzog. They became known as the "Speed Freak Killers." They targeted random victims and killed them for fun. The number of their victims is believed to be between four and seventy-two.

In 1984, they killed Henry Lee Howell. Shermantine shot Howell while he was parked on the side of a remote highway in California. Later that same year, on November 27, they murdered two drifters, Howard King and Paul Raymond Cavanaugh, on Roberts Island. Shermantine shot King while he was sitting in his car and then killed Cavanaugh by dragging him out and shooting him too.

They continued their violent acts into the mid-1980s. In December 1984, Kimberly Ann Billy vanished from Stockton, California. Joann Hobson, only 16 years old, disappeared in August 1985. Their remains were later found in an abandoned well, recovered after Shermantine provided information about their locations.

Another of their victims was Roberta Ray “Robin” Jones Armtrout. She was last seen on September 8, 1985. Shermantine killed her after a night out and discarded her body in a creek.

Chevelle “Chevy” Wheeler, aged 16, also fell victim to Shermantine. She disappeared when she left Franklin High School in October 1985, after stating she was going to a cabin with Shermantine. Authorities later linked him to her disappearance, and evidence found in his cabin confirmed it.

Their violent spree continued with Cynthia Ann “Cyndi” Vanderheiden, who went missing in November 1998. Eventually, Shermantine and Herzog were arrested in March 1999.

During Shermantine’s trial in 2001, witnesses spoke about his violent behavior, including sexual assaults on several women. He was convicted of four murders and sentenced to death, where he remains on death row at San Quentin State Prison.

In 2010, while still incarcerated, Shermantine sent letters to his sister detailing the locations of some of their victims. In February 2012, authorities discovered over 300 human bone fragments at a well he identified. This site held the remains of Kimberly Ann Billy and Joann Hobson, along with other unidentifiable remains.

Shermantine later led investigators to other sites believed to contain more victims, but many searches yielded no results. After Herzog committed suicide in 2012, Shermantine continued to make claims about more victims and where they might be found, but these claims were often misleading. He suggested many more victims but refused to divulge information without financial incentives.

The investigation into their crimes has faced various allegations of negligence and mishandling of evidence, raising concerns among victims' families. The case of the Speed Freak Killers remains a significant and tragic part of California's criminal history.