Neighbours and friends of Jeffrey Lee Parson - charged with spreading an internet virus - have described him as a quiet and lonely youth who may not have known what he was getting into.
Parson reportedly asked for help with a hacking programme
"I can't see him intending to do anything wrong," Kathy Noor, a neighbour of the 18-year-old from the state of Minnesota told the local press.
Nina Bauernfield, a friend of the 18-year-old, said he had told her weeks ago that he had planted a variant of the so-called MSBlast worm, which infected hundreds of thousands of computers worldwide and causing them to crash.
"He said that he sent out a virus and didn't know what it was going to do exactly, but it was out there and it was modified original," the 16-year-old girl told local reporters.
"When he found out this was a huge thing he felt really bad. He was really worried, he was freaking out."
Jeffrey's parents, Rita and Bob Parsons, have refused to comment on the case.
Other local residents in the town of Hopkins also expressed disbelief, describing him as "nice" and "quiet".
"I think he is just a young man who got sucked into something over his head," said neighbour Maureen Carriveau.
Ms Carriveau and other neighbours described the high-school student as a loner, who had been troubled by his size when he was younger.
The six-foot-four (1.92m), 320-pound (145-kilogram) youth "felt no one would like him because of his size", according to Ms Carriveau.
Another Hopkins resident told the Star Tribune that Jeffrey had been taunted by other children because of his size.
Neighbour Curtis Mackey said the youth had few friends and just had "one kid he hangs out with typically".
According to Minnesota Public Radio (MPR), Mr Parson posted questions on websites asking for help with a programme that hacks a type of messaging system.
He also spent a considerable amount of time playing the online game Counterstrike, MPR reported.
If found guilty, Jeffrey Parson faces up to 10 years in prison and a $250,000 fine.