Joseph-Albert Guay was born on September 22, 1917, in Charny, Quebec. He was the youngest of five children in his family. When Joseph was just five years old, his father died in a railroad accident. This tragic event forced the family to move to a suburb of Quebec City.

As Joseph grew up, he faced many challenges. He obtained a draft deferment during World War II, which allowed him to avoid military service. In August 1941, he married Rita Morel. They moved to Quebec City, where Joseph found work at the Arsenal and sold jewelry and watches for extra money. While working, he met a watchmaker named Généreux Ruest. The two became close friends, and Joseph also grew close to Ruest's sister, Marguerite Pitre.

As the war came to an end, Joseph transitioned to selling jewelry fulltime. He offered a variety of items, including engagement rings and watches. If a watch needed repair, Joseph would take it to Ruest's workshop. During this time, Généreux Ruest and his wife moved to Sept-Îles and welcomed a daughter in 1945.

In the summer of 1947, Joseph-Albert Guay met Marie-Ange Robitaille, a 17-year-old waitress. Guay was married but started an affair with her. He introduced himself to her parents under the fake name "Roger Angers." As their relationship continued, Guay's wife found out about the affair in November 1948. This led to conflicts that resulted in Robitaille being kicked out of her house. Guay helped Robitaille by asking a friend, Marguerite Pitre, to take her in at her boarding house.

At first, Robitaille wanted to return home, but Guay convinced her to stay with him. He threatened her to prevent her from leaving, even resorting to burning her gloves to scare her. By April 1949, Guay attempted to hire someone to kill his wife with poisoned wine, but the person refused. Later that June, Guay's wife moved in with her mother, and Robitaille finally left him.

In a desperate move, Guay confronted Robitaille while she walked to work, pulling out a gun and threatening her. This led to his arrest for attempted assault. After a brief legal battle, his charge was reduced, and he was released. Two days later, Guay convinced Robitaille to flee to Montreal with him again.

As their relationship became strained, Guay realized he needed to eliminate his wife to be with Robitaille. He recruited Pitre and another friend, Généreux Ruest, to help him with a scheme to kill his wife. Together, they plotted against her, but their initial plans with dynamite failed to execute as intended. Guay then decided to blow up an airplane while his wife was on board.

On September 9, 1949, Guay planted a bomb on Canadian Pacific Air Lines Flight 108. The plane exploded over Cap Tourmente, leading to the deaths of all 23 people on board, including Guay's wife. Once investigators looked into the crash, they quickly determined that it was not an accident. They traced clues to Pitre, who eventually confessed to her role in the plot.

Guay was arrested two weeks after the crash and was charged with murder. During his trial, he showed little interest in the proceedings and did not testify. He was found guilty and sentenced to death by hanging. His accomplices, Ruest and Pitre, were tried and also sentenced to death. Guay was executed on January 12, 1951. Ruest and Pitre were executed in the following years, with Pitre being the last woman hanged in Canada.