By Katty Kay
BBC correspondent in Chesapeake, Virginia
Lee Boyd Malvo was in court in this Virginia town 200 miles (320 km) south of Washington for just 15 minutes in an appearance carefully orchestrated to show the boy in him. He wore a striped blue sweater and his curly hair was cut short.
Asked what he pleaded, Mr Malvo replied "Not guilty" to two counts of murder and one count of unlawful use of a firearm.
Malvo's age is set to be a key factor in his defence
In a soft voice he then politely answered, "Yes Ma'am" to the judge's questions about whether he understood the charges related to last year's sniper attacks around Washington.
Throughout the brief hearing his lawyer kept his hand on Mr Malvo's shoulder in a gesture of paternal support.
Little surprise perhaps that the defence's main strategy is to portray Mr Malvo as a boy led astray by an older man.
How else, perhaps, to account for the troubling question of what allegedly led the then 17-year-old into the midst of the sniper killings which terrified Washington for three long weeks?
At the opening hearing Mr Malvo's lawyers explained that he was in fact pleading "not guilty on grounds of insanity".
Lee Malvo was born in Jamaica. His father abandoned him and his mother used to leave him with for months on end with sympathetic adults. According to people who knew him then, Lee was lonely, innocent and easily influenced.
He met John Allen Muhammad, the other accused sniper, on the island of Antigua in 2000 when he was 15 years old.
Within months the boy converted to Mr Muhammad's religion, Islam, and started to call him "father".
At the heart of this case are our own perceptions of youth
People who met the pair as they travelled through the United States say the boy seemed under the thumb of the older man.
The defence lawyers say they will argue that Mr Malvo was manipulated by Mr Muhammad to perform the killings and that the older man, a 10-year military veteran, trained him - almost as a commanding officer would - to be the sniper.
The lawyers claim that indoctrination is a form of insanity.
But a very different picture of this young man emerges from the prosecution.
Mr Malvo's fingerprints are on the murder weapon and evidence points to him pulling the trigger, they say.
The chief prosecutor plans to argue that Mr Malvo knew exactly what he was doing and that even after his arrest he boasted about the killings to police guards, saying they were a mission and he would do it all over again.
So which is the real Lee Malvo? The young, innocent boy who fell into the wrong hands after his own parents neglected him or the calculating killer who appeared to take a cold pleasure in taunting the police?
At the heart of this case are our own perceptions of youth.
Mr Malvo was a juvenile at the time of the sniper killings. Would that make him less responsible? Will it and should it be enough to get him a lesser punishment if indeed he is convicted?
Over the next few weeks this trial will deal with the specifics of Mr Malvo's alleged involvement in the 10 sniper Washington killings of last year, but it is also raising broader questions about America's system of justice and how far children are responsible for their actions.