Thomas Eugene Creech was born on September 9, 1950, in Hamilton, Ohio. He had a difficult childhood. His parents often fought, which created a tense home environment. Eventually, they got divorced. After the divorce, Creech lived with his father. Later in life, when Creech was a teenager, his father died unexpectedly in front of him. This event was traumatic, and Creech claimed that he attacked a nurse who tried to help his father.

After this, Creech's life became hard to track. He ran away from home and started drifting across the country. In December 1969, he was arrested for unarmed robbery and was sentenced to two to fifty years in prison. He was released on parole in 1971. In 1973, Creech married a 17-year-old girl named Thomasine Loren White from Boise, Idaho. She is said to have been involved in some of his future crimes. She later ended up in a psychiatric hospital in Salem, Oregon, where she took her own life. Creech wrote in a letter that her death was connected to severe injuries from a violent attack by a group of men.

On August 22, 1973, Creech broke his parole by stealing 13 cartons of cigarettes in Portland. Although he faced charges, they were dropped after he was admitted to a psychiatric hospital for evaluation. He behaved well there and was released after a week. Creech later secured a job as a sexton at St. Marks Episcopal Church in Portland but quit after a man's body was discovered in his living quarters. Shortly after, he moved to Idaho with a new girlfriend named Carol Spaulding, who was also 17 years old at the time.

On November 6, 1974, Thomas Eugene Creech and Carol Spaulding were hitchhiking in Idaho when they were picked up by two house painters, Edward Thomas Arnold and John Wayne Bradford. During the ride, Creech pulled out a rifle and shot both men in the head. He then hid their bodies in a barrow pit along Highway 55. Their car was found the next day, along with the bodies.

A few days later, Creech and Spaulding were arrested in Glenns Ferry, Idaho, after being identified as fugitives wanted for murder. While they faced murder charges, Creech was also a suspect in two other murders in Oregon. He was briefly held in jail and later moved to a more secure facility in Boise.

After his arrest, Creech attempted to take his own life but was restrained by prison guards. He continued to cause problems while imprisoned, including attacking a cellmate. Eventually, he faced trial for the murders of Arnold and Bradford, during which he shocked many by confessing to multiple murders across various states.

In October 1975, during his trial, Creech claimed responsibility for 42 murders. Although authorities linked him to nine confirmed victims, they deemed most of his confessions to be exaggerated or false. He was found guilty of murdering Arnold and Bradford and was sentenced to death in 1976. This execution was delayed due to appeals, and he later offered to stand trial for other killings.

Creech committed another murder while incarcerated in 1981, killing an inmate named David Dale Jensen. He pleaded guilty to this murder as well and was again sentenced to death. Creech remained on death row in Idaho for many years, appealing his sentence multiple times.

Updates in 2023 revealed that Creech was still the longest-serving inmate on death row in Idaho, with numerous requests for clemency being denied. On October 12, 2023, his execution date was set for November 8, but it was canceled due to a failed attempt to establish the necessary intravenous line for lethal injection. His current status remains on death row.