Marguerite Pitre was born on September 5, 1908, in Saint-Octave-de-Métis, Quebec, Canada. Pitre became a well-known figure in her community as she later ran a boarding house in Saint-Roch. 

Her neighbors and the press referred to her as "Madame le Corbeau," which means "Madame Raven," likely because she often wore black clothing.

In the summer of 1947, Guay began an affair with 17-year-old Marie-Ange Robitaille. She was under false pretenses about his marital status. By November 1948, Guay's wife found out about the affair, which led to complications for Robitaille. After initially being kicked out by her parents, she later wanted to return home but was coerced back to Guay.

In April 1949, Guay planned to kill his wife. He asked a family friend, Lucien Carreau, to help him but was refused. After Guay's wife moved out, Robitaille attempted to leave him, but Guay threatened her with a gun. He was arrested for this incident but managed to get a reduced charge. Two days later, Guay convinced Robitaille to flee with him again.

As the relationship turned sour, Guay became serious about killing his wife so he could be with Robitaille. He recruited Marguerite Pitre and his friend Ruest to help him. Pitre bought dynamite under false pretenses and gave it to Guay, who then planned to blow up an airplane with his wife on board.

On September 9, 1949, Flight 108 was destroyed by a bomb placed on the plane. It crashed, resulting in the deaths of all 23 people on board. Investigators quickly linked the explosion to Guay, Pitre, and Ruest.

Pitre initially attempted to distance herself from the crime but later confessed to delivering a package to the airport for Guay. Guay was arrested, and evidence pointed to his guilt. He was tried and found guilty of murder in March 1950. He received a death sentence.

Ruest and Pitre were also arrested. They had their trials in 1951, and both were convicted and sentenced to death by hanging. Guay was executed first, followed by Ruest in 1952, and then Pitre in January 1953. She was the last woman to be hanged in Canada.