John Dwight Canaday was born in 1945 in Washington State. Details about his early life are limited, but records indicate he served honorably in the U.S. Navy during the Vietnam War. After his military service, Canaday returned to Washington and took up employment with the Seattle Water Department.​

By the late 1960s, Canaday's personal life was in turmoil. He was divorced and reportedly struggling with anger and emotional instability. These issues, coupled with his experiences during the war, may have contributed to his descent into violent behavior.​

Canaday's known killing spree began on December 17, 1968, with the murder of 16-year-old Sandra Bowman, a pregnant newlywed. Bowman was found in her Seattle apartment, stabbed 57 times, with her hands bound behind her back. The case went cold for decades.

On January 4, 1969, 21-year-old Mary Annabelle Bjornson disappeared from her Seattle apartment. Evidence later revealed that Canaday had lured her out under the pretense of car trouble, then abducted, raped, and strangled her. Just weeks later, on January 24, 1969, 20-year-old Lynne Carol Tuski vanished while walking to her car. Canaday similarly abducted, raped, and murdered her, disposing of her body in a remote area.

Canaday's arrest on February 22, 1969, stemmed from the kidnapping of another woman, Eunice Thomas, whom he held captive for nearly three days. Her rescue led authorities to investigate Canaday further. ​In March 1969, Canaday confessed to the murders of Bjornson and Tuski, leading police to their bodies. He was convicted and sentenced to death, but his sentence was commuted to life imprisonment in 1972. ​

In 2004, DNA evidence linked Canaday to the long-unsolved murder of Sandra Bowman. Confronted with this evidence, he confessed, stating, "Yes, I killed her." He received a third life sentence for this crime. ​Canaday died of natural causes on December 26, 2012, while serving his sentences at Clallam Bay Corrections Center in Washington State. ​