Asperger's is a mild form of autism. Asperger's is associated with difficulty making social connections but is not normally associated with predilection to violent behavior.
Krumm seemed normal to relatives as recently as three years ago, but then had a falling-out with his father. An uncle, Jon Sims, of Cheyenne, said he tried several times in recent years to reach his nephew by email, without success.
"As far as I know, he lived alone and had some social skill problems," Sims said.
Sims and Nichols both said they didn't know of any official diagnosis of Asperger's, but that Krumm may have diagnosed himself. Nichols said James Krumm told her that his son blamed him for Asperger's.
"He said 'He hates me. He blames me for this Asperger's,' " she said.
Police say Krumm shot 56-year-old James Krumm with an arrow and stabbed him in his Casper College classroom Friday. The six or so students in the computer science class escaped unhurt.
Earlier, Krumm fatally stabbed his father's girlfriend, 42-year-old Heidi Arnold, at the home she and James Krumm shared in a quiet neighborhood about two miles from campus. Arnold was a math instructor at Casper College.
Christopher Krumm fatally stabbed himself in the classroom after attacking his father. Nobody saw the final moments of the struggle all students were able to flee unhurt but police say Christopher Krumm stabbed his father in the chest.
Police arrived to find James Krumm dead and Christopher Krumm breathing his last breaths; he died in the classroom. Authorities locked down the campus for two hours until they were reassured there were no other attackers.
Police said Krumm acted alone and that his motive was unclear. No suicide note was reported found.
Krumm had been living in an apartment house in Vernon, Conn., and drove to Casper a few days before the attack.
Nichols said she only knew her nephew to be polite and amiable. She said he was very close to his mother, Carol Krumm, who died of breast cancer in 2005.
Nichols said her nephew was friendly with his cousins but didn't seem to have any other friends his own age growing up.
"He was always comfortable around adults, and I guess kids in his class seemed too immature for him," Nichols said.
"I'm just real sad to lose him. I'm sad. I really loved him. It was hard losing my sister and now this. I wonder what's next. But he was obviously a lost soul, and I hope he's at peace now."
She described her nephew as a "borderline genius." As a high school student in Casper, Krumm had amassed 59 credits taking math, computer science, physics and violin at Casper College, school spokesman Rich Fujita said Monday.
A typical major requires about 64 credits for a degree from the two-year school.
Krumm most recently worked as a groundman for Broadband Access Services, a company that builds cable lines along roadways throughout New England, but he quit Tuesday.
A company spokeswoman said he worked for the Connecticut office for several months but she didn't have any details about his departure.
Krumm had lived in Vernon for the past few months in a three-story rooming house. Residents share a common bathroom on each floor. The rooms don't have kitchens so the only way to cook is on a hot plate or with a microwave.
Police searched Krumm's room at the request of Wyoming authorities and found some items, detective Jim Grady said. The Hartford, Conn., bomb squad assisted in the search, but no hazardous devices were found. Police said they turned over some paper records, a computer printer and unidentified other items that were requested by authorities in Casper.
Police in Connecticut said Krumm applied for a pistol permit Oct. 17 but the permit was still pending and wasn't issued.
Krumm got a bachelor's of science degree from Colorado State University in 2008, school spokesman Mike Hooker said.
According to the school's website, he studied high-resolution imaging with lasers for his senior project. His faculty adviser, Carmen S. Menoni, referred questions to a school spokesman.
His uncle said he last saw his nephew around the time he got his master's three years ago.
"We had him for dinner. He seemed fairly normal at that point to me. But then when he went back East we lost contact with him and weren't able to re-establish contact, so I don't know what was going on," Jon Sims said.
Nichols said she emailed her nephew a year ago and asked for his address to send him a birthday card, but he responded that he wouldn't give it to her because he didn't want his dad to find him.
"I wish we could have been in contact with him," Sims said. "We tried several times, but unsuccessfully. But, you know, there's only so much you can do."
A memorial service is planned at Casper College on Tuesday.