Relatives, friends and former teachers of sniper suspect Lee Boyd Malvo (search) described him Tuesday as an obedient, inquisitive and cheerful boy, but said he sometimes appeared emotionally vulnerable.

"He was dependable and hardworking, and whenever he was given a task he would pursue it to the end," said Beryl Spence Jack, Malvo's sixth-grade teacher in Jamaica.

Witnesses testified that Malvo attended a number of different schools around the Caribbean while his mother looked for work, and lived with a string of people who were willing to take him in.

Malvo's lawyers have argued that his childhood of abandonment and uprooting, as well as a Jamaican culture that emphasized discipline and obedience, made him especially susceptible to the influence of sniper mastermind John Allen Muhammad (search).

They do not dispute that he took part in the sniper attacks, but argue he should be found innocent of murder because Muhammad's indoctrination made him legally insane. Malvo could face the death penalty if convicted in the Oct. 14, 2002, killing of Linda Franklin (search) outside a Home Depot. Muhammad was tried separately, and his jury recommended Monday that he be put to death.

Malvo's uncle, John Benjamin Lawrence, recalled him as a 9-year-old boy who constantly asked questions.

Lawrence's wife, Marie, called Malvo "very obedient," but said she whipped him with a strap on rare occasions to discipline him. "He tried to obey, because I don't joke," Lawrence said.

On her way out of the courtroom, she wept, and defense attorney Michael Arif said later that Malvo was "extremely distraught" during the testimony of his aunt and uncle.

Malvo put his head down during the testimony, and Arif rested his hand on Malvo's back. Later, as friends appeared on his behalf, Malvo smiled and occasionally laughed, as when one witness mentioned a former girlfriend.

Esmie McLeod, one of Malvo's teachers at York Castle High School in Brown's Town, Jamaica, described him as "spontaneous, effervescent and very witty," but said that she was concerned about the effect of constant uprooting in his life.

She said she saw "an emotional vulnerability about Lee."

The principal of another school testified that Malvo's mother approved the designation of Muhammad as his guardian. Malvo's lawyers have said the mother, Una James, will not appear at the trial because they could not get permission for her to come to the United States from Jamaica. She was deported last year.

Rosalind Aaron, of a Seventh-Day Adventist school on the Caribbean island of Antigua, said Muhammad once identified himself as Malvo's uncle.

Aaron, who taught Malvo in the 11th grade, said he left the school about two weeks after she took a Quran away from him. She said she did not want him spreading Muslim ideas in a Christian school.

Robert Holmes, a former business partner of Muhammad from Washington, said Malvo and Muhammad frequently worked out together and visited a local shooting range. He described Malvo as a "happy-go-lucky" teenager who never refused to follow Muhammad's directions or commands.