It says that Heidi lived with the professor so presumably was his girlfriend. No mention of Chris Krumm's mother. If she is still alive perhaps there was a nasty divorce and the son decided to take it out on his father and the "other woman."
According to Herodotus, the ancient Persians believed that no man has ever killed his own father or mother--in cases where this has apparently happened, the son was either a changeling or born out of wedlock (The Histories, Book 1, chapter 137)
Here are the entries in the Casper directory. They haven't cleaned up yet. She was a math instuctor, he was comuputer science.
http://www.caspercollege.edu/directory/arnold_heidi.html
http://www.caspercollege.edu/directory/krumm_james.html