Oscar Joseph Comery was born in July 1886 in Canada to French Canadian parents, Joseph Comery (also spelled Comire) and Celine Boisvert. He later immigrated to the United States, settling in New Hampshire, where he worked as a chauffeur. 

On November 29, 1914, Comery murdered his wife by poisoning her. He substituted her regular quinine medication with strychnine, leading to her death. An autopsy confirmed strychnine poisoning as the cause. Comery was arrested on January 1, 1915, and during his trial on February 8, 1915, he pleaded guilty to first-degree murder, anticipating a life sentence. However, he was sentenced to death and executed by hanging at the New Hampshire State Prison on February 18, 1916, at the age of 34. Comery was one of only three individuals executed by New Hampshire in the 20th century.