Anthony Guy Walker was born on July 11, 1957, in Michigan, USA. There is little publicly available information about his childhood or family upbringing, and his early years have not been well-documented.

In 1975, at just 18 years old, Walker was arrested in Adrian, Michigan, for the kidnapping and rape of a woman. Although the kidnapping charge was dropped, he pleaded guilty to second-degree criminal sexual conduct and served a short prison sentence. Upon his parole in January 1979, Walker resumed criminal activity almost immediately.

Anthony Guy Walker's first admitted murder was committed in 1975. He killed 24-year-old Arleen Salcedo, whose body was found on September 22, 1975, in a field. The cause of her death could not be determined, and the case went unsolved for some time. Later that year, Walker was arrested for a separate violent crime and sentenced to prison. He was released in January 1979.

On January 15, 1979, Walker broke into a home in Adrian, Michigan. Inside were 24-year-old Yolanda Torres Madison, her 11-month-old daughter Jessica, and Yolanda's friend Theresa Carey. Walker tied up and beat the two women before shooting them. He then stole items from the house and set it on fire. The fire caused the infant to suffocate from smoke inhalation. When Yolanda’s brother went to the house and noticed the smoke, he called the fire department. Emergency responders found all three bodies when they arrived.

In addition to these murders, Walker was involved in another death on March 1, when he was paid $2,000 to kill 28-year-old Floyd Beatty. Beatty's body was discovered near his home the following day.

While in prison in 1986, Walker paid an inmate to kill 40-year-old Daniel A. Staggs. Staggs was later found dead in the prison, having been stabbed.

After he was released from prison in June 1993, Walker was arrested a year and a half later for sex crimes. He was convicted of two counts of first-degree criminal sexual conduct and sentenced to life in prison.

In 2010, after advancements in technology and new witnesses coming forward, cold case investigators charged Walker in the Madison-Carey murders. During the trial, he pleaded guilty to killing both women but denied starting the fire that killed Jessica. He also confessed to the murders of Arleen Salcedo and Floyd Beatty, as well as ordering the murder of Daniel Staggs. In exchange for his confessions, he was not prosecuted for these other murders.

Walker was ultimately sentenced to three life terms in prison. He showed no remorse for his actions. His attorney suggested that Walker might have been involved in over 30 murders in Michigan and possibly other states. Walker himself offered details about several actions he claimed to have taken.

In 2015, a documentary aired that focused on the investigation and prosecution of Walker for the murders he committed.