John Errol Ferguson was born 27 February 1948 and grew up in Miami-Dade County, Florida, as the fourth of eight children. Known to psychiatrists from the age of ten, Ferguson exhibited troubling behavior throughout his youth. His father died when he was thirteen, leaving his mother to raise the large family alone. He dropped out of school after repeating ninth grade three times and developed a juvenile criminal record.

His first major police encounter occurred at age 13, when he was caught driving someone else’s car without permission. This began a pattern of arrests and antisocial behavior. In 1969, during a traffic stop, Ferguson disarmed Officer Edward Hartman, ordered him to kneel and beg for his life, and fired four shots — all missed. Hartman then shot Ferguson four times, critically wounding him.

By 1975, psychiatrists considered him “dangerous to himself and others … homicidal” and strongly advised against release. Despite these warnings, Ferguson successfully manipulated doctors by feigning delusions. He bragged about “psyching them out” to friends. After multiple escapes from hospitals, he was sent to the more secure Florida State Hospital, but in June 1976 was released back to Miami after being judged “competent” despite continued warnings.

On October 30, 1974, James Ward, a 40-year-old escapee from a mental hospital, was found murdered by a shotgun blast in Collier County, Florida. Just two days later, on November 1, Joseph Walters was discovered dead near railroad tracks in Miami, having suffered a shotgun blast and multiple handgun wounds. These cases remained unsolved until February 1977, when Edward Eugene Oliver, already convicted for Ward's murder, confessed to both killings. Oliver implicated Ferguson as the shooter in both incidents, stating that the victims were part of a gang involved in robberies and that disputes over stolen merchandise led to their deaths. Despite Oliver's confession and passing a polygraph test, Ferguson was never prosecuted for these 1974 murders.

On July 27, 1977, Ferguson, along with accomplices Marvin Francois and Beauford White, orchestrated a home invasion in Carol City, Florida. Posing as a utility worker, Ferguson gained entry to the home of Margaret Wooden. Over the next several hours, they bound and blindfolded eight individuals who arrived at the house. The victims were then executed with gunshots to the head; six died, and two survived to testify against the perpetrators. This incident was the largest mass murder in Miami-Dade County at the time.

On January 8, 1978, Ferguson committed another heinous act by murdering two teenagers, Belinda Worley and Brian Glenfeldt, in Hialeah, Florida. The couple was last seen leaving a Youth for Christ meeting. The next morning, their bodies were discovered in a wooded area; Brian had been shot multiple times, and Belinda had been raped and shot in the back of the head. Jewelry was missing from Belinda's body, and Brian's wallet was found empty, indicating robbery as a motive.

Ferguson was arrested on April 5, 1978, and subsequently convicted for the Carol City and Hialeah murders. During his trials, debates over his mental competency arose, with defense attorneys arguing that he suffered from paranoid schizophrenia. Despite these claims, courts found him competent to stand trial, and he was sentenced to death. Ferguson spent over three decades on death row, during which he continued to exhibit signs of mental illness, including delusions of being the "Prince of God."

After numerous appeals focusing on his mental health, Ferguson was executed by lethal injection on August 5, 2013. His case remains a controversial example of the intersection between mental illness and the criminal justice system.