The guy has/had a dating profile on
Spiritual Passions.
His user name was Ironcross45.
This is probably where the report of "mixed race" comes from, however the captures at archive.com shows that the dating profile was changed several times - after he was dead. Allegedly the
ethnicity and the
political views, among other items, were changed.
BREAKING: Internet Trolls Altered Chris Harper Mercer's Online Profile Today - Now Says He's "Conservative"
From the NYT:
Mercer was a withdrawn young man who neighbors said wore the same outfit every day — combat boots, green Army pants and a white T-shirt — and was close to his mother, who fiercely protected him.
http://www.nytimes.com/2015/10/03/us/chris-harper-mercer-umpqua-community-college-shooting.html
I will speculate that he was a 'mommas boy' who was always sheltered from every aspect of life, a social cripple who was isolated from friendships and normal human interaction, and who lashed out to get the attention that he had been deprived of by being raised as a recluse. That, or he's just batschit crazy.