Loren Joseph Herzog and Wesley Howard Shermantine, Jr., a.k.a. ""The Speed Freak Killers"", were a pair of rapists and serial killers.

Herzog and Shermantine were both born in the farming town of Linden, California, and lived a street away from each other. Because there weren't many other children to play within their neighborhood, they befriended each other and apparently had no other friends. The two spent their childhood exploring the entire area of San Joaquin County. Shermantine's father would usually take both boys on hunting and fishing trips until they were old enough to go on their own. He would also spoil Shermantine with many gifts. Herzog had a brief affair with a woman named Kim Vanderheiden, the older sister of Cynthia Vanderheiden, who would later become one of his victims. Herzog and Shermantine remained best friends through their high school years and adulthood. They also took pleasure in bullying other people, as well as drinking and using drugs, especially methamphetamine, in their apartment in nearby Stockton. They also became frequent barflies at Cynthia and Kim's father's bar.

Shortly after graduating from Linden High School, Herzog and Shermantine committed their known killings. Howard King and Paul Cavanaugh were their first victims, both shot to death in their car. That same year, Shermantine fatally shot a man named Henry Powell. Both Powell's murder and the King-Cavanaugh case went unsolved until Herzog and Shermantine's arrests. A year later, the nude body of Robin Armtrout was found; she was raped and stabbed to death. Later, a woman named Chevelle ""Chevy"" Wheeler skipped class to meet with Shermantine, but she was abducted by him and presumably raped before being killed by unknown causes. During the search for Wheeler, police looked at Shermantine as a person of interest, and a search warrant for Shermantine's hunting cabin was requested. There, police found negative-type blood, and though Wheeler had negative blood, a lack of other physical evidence resulted in Shermantine not being arrested for her murder. The case went cold until DNA testings were available, which showed that the blood was most likely from Wheeler.

According to Herzog, Shermantine had also killed an unnamed Utah hunter who had crossed their way in 1994, by shooting him to death. In 1998, Cyndi Vanderheiden approached Herzog and Shermantine in a bar and asked for drugs. Instead, she was abducted by them and raped by Shermantine, then dragged to an isolated location and stabbed to death. Her body was put inside Shermantine's car and dumped in a different location. Both were arrested on March 17, 1999, for the murder of Vanderheiden after her blood was found inside Shermantine's car. In prison, Shermantine denied any involvement with Wheeler or Vanderheiden, despite the fact that her blood was found in his car.