Marjorie Diehl-Armstrong (February 26, 1949 – April 4, 2017) had a history of suffering from multiple mental illnesses including bipolar disorder, since her early teens, and seems to have been a serial killer. Before her mental health deteriorated in her twenties, Diehl-Armstrong was an "exemplary student" in high school and earned a master's degree from Gannon College. In 1984, she shot her boyfriend Robert Thomas six times as he lay on the couch but was acquitted on claims of self-defense. Her husband and several other partners also died under suspicious circumstances. Diehl-Armstrong died from breast cancer in prison on April 4, 2017, at the age of 68.