"This is a key part of who Lee Boyd Malvo is - a need to feel superior, a need to be in power," Nelson said.
Nelson offered yet another theory of Malvo's behavior - that of "a vulnerable and manipulative young man" - based in part on letters Malvo wrote from jail in late summer or early fall this year, "after he has been deprogrammed."
He noted advice Malvo gave another inmate in the Fairfax County Detention Center. In handwritten letters full of profanity, he told the inmate, "Pacman," not to draw attention to himself, but to quietly plot his escape, starting with familiarizing himself with the guards and their habits.
"Get a job, study the facility/prison, make a map. Look for security weaknesses. And when you find one, wait for your best chance and leave," Malvo recommended.
"My strategy works for me because my enemy does not know me," Malvo wrote, explaining that he is underestimated. "I play the stupid fool."
Inmates are not allowed to send each other missives. Malvo had to mail the letters - introduced by the prosecution in its one-day rebuttal - to someone who mailed them to "Pacman."
"If you fight them all the time, they will always be looking at you," Malvo wrote in one letter. "But if you never resist, when you do resist, they will be caught bye [sic] surprise, never expected it, wouldn't even dream you were capable of such cruelty, hatred, brains."
"You must be able to sit at the table with your enemy and not let them know that you 'hate there [sic] guts.' The key to achieving this is the ability to mask your emotions."
Malvo also tells of a dream in which a man who is apparently Muhammad ignores him. Malvo writes that he comes upon Muhammad on a bench and that the older man looks him straight in the eye and denies his existence.
As he has appeared throughout the trial, Malvo seems remorseless and unrepentent in the letters.
He writes in one, "I don't know what's going to happen, man, no sweat though. I'm prepared for death, what can be worse?"
Sun staff writer Stephen Kiehl contributed to this article.