It was later revealed he had previously murdered his father's girlfriend, Heidi Arnold, also a teacher at said college, by stabbing her to death at their residence.
[3] At the time of the attacks, James Krumm was actively dating Heidi Jeannette Arnold, aged 42, who also worked at Casper College as a math instructor.
Whilst taking a class in Casper College, his calculus teacher Mickie Goodro remembered him as being one of the smartest students she'd ever had "but his social skills were not wonderful."
[5] On Friday, November 30, 2012, Christopher Krumm traveled 2,000 miles from his home in Connecticut to the residence of his father and Heidi Arnold in Wyoming.
Despite the arrow going fully through his head, Jim rose up and attacked his son, allowing his six students to escape before any harm could come to them.
During the crime scene investigations, Arnold’s body as left outside the house for multiple hours, which local police later apologized for.