On his blog, an online diary that he had kept since September 2002, Underwood described himself as "single, bored, and lonely, but other than that, pretty happy."
He mentions cannibalism, asking "If you were a cannibal, what would you wear to dinner?" and responding: "The skin of last night's main course."
In an entry dated February 4, 2006, Underwood wrote that he struggled with depression and social interaction.
"Pretty much the only time I believe in God is when I blame him for something," he said. "Or, when I'm really depressed, to cry and beg him to make me better, to make whatever is wrong in my brain go away, so that I can live like a normal person.
"That's all I want in life, is to be able to live like a normal person."
He wrote that he rarely left his apartment for long stretches, except to go to work and to buy food. "I just sit here at the computer every minute of the day, when I'm not at work. A week or so ago, I spent my day off sitting here at the computer, barely moving from the chair, for 14 hours."
He said one of his main interests was the online role-playing game "Kingdom of Loathing," in which stick figures battle one another.
In September 2004, he wrote that his depression deepened after several months without taking the medication Lexapro, an antidepressant also used in the treatment of anxiety disorders.
"For example, my fantasies are just getting weirder and weirder. Dangerously weird," he wrote. "If people knew the kinds of things I think about anymore, I'd probably be locked away. No probably about it, I know I would be."
Is this one of the side effects of the technological age? Let's hope not.