"We have lived with death," said Victoria Snider, the sister of victim James L. "Sonny" Buchanan, who was killed in Maryland, said. "We have lived with watching others die."
Marion Lewis, whose daughter, Lori Ann Lewis-Rivera, was shot and killed by a sniper bullet while cleaning her minivan at a Maryland gas station, said the jurors should be ashamed.
"I'm very disappointed in the American justice system," Lewis said. "Our society has now been sentenced to the responsibility of seeing to this man's health and welfare for the next 30 or 40 years, and that's unconscionable."
A jury Tuesday sentenced the 18-year-old convicted killer to life in prison, agreeing with defense lawyers' portrayal of Malvo as an impressionable boy who fell under Muhammad's murderous spell.
Malvo was convicted of murder last week in the shooting of FBI analyst Linda Franklin, who was cut down by a single bullet to the head outside a Home Depot in Washington's Northern Virginia suburbs. Malvo was 17 at the time.
Franklin's daughter, Katrina Hannum, shook her head and cried when the sentence was read. She did not speak to reporters.
Both Muhammad and Malvo could still be tried for other shootings.
"Malvo is not out of the woods yet. He still faces potential murder trials in Maryland, the District of Columbia and Alabama; and in Alabama he may face a capital murder trial. So you can bet now that prosecutors in those jurisdictions will be angling now to prosecute him again," says CBSNews.com Legal Analyst Cohen.
The judge must impose life without parole when Malvo is formally sentenced March 10 for his part in the three-week reign of terror that left 10 people dead in and around the nation's capital in October 2002.
Malvo, wearing a blue sweater that made him look like a schoolboy, sat expressionless, his elbows on the defense table.
The jury took eight-and-a-half hours over two days to decide his fate.
Stunned prosecutors could not hide their disappointment, reports CBS News Correspondent Jim Stewart.
"Of course, I'm not happy with the decision, but it's the American way," said Prosecutor Robert F. Horan Jr.
The trial was "an extremely difficult journey for everyone," jury foreman Jim Wolfcale said after the verdict. "This case was both mentally challenging and emotionally exhausting."
Wolfcale, reading from a statement as six other jurors stood by, added that the jury felt "heartfelt sympathy" for the victims' families and friends. The other jurors declined comment.
Wolfcale did not discuss why the jury decided on life, but prosecutors and defense lawyers agreed that Malvo's youth played a major role.
Horan said afterward that Malvo was "very lucky that he looks a lot younger than he is." And he suggested the timing of the deliberations just days before Christmas affected the jury.
"We used to have a theory when I was a very young prosecutor that whatever you do, don't try one on Christmas week," Horan said.
Defense attorney Craig Cooley said Malvo was relieved by the sentence, but "on the other hand he's 18, contemplating living the rest of his natural life in a penitentiary setting." He said the conviction will be appealed to the Virginia Supreme Court.
"This is a surprise, a shock, especially given the amount and nature of the evidence against him. Malvo ought to thank his attorneys for coming up with an insanity defense that was designed to educate jurors from the start of the trial about Malvo's background and his ill-fated relationship with the older sniper, John Muhammad," says CBSNews.com Legal Analyst Andrew Cohen.
Last month, Muhammad, 42, was found guilty of murder, and the jury recommended the death penalty. The judge in that case could still overrule the jury when he formally sentences Muhammad.
Cooley had argued that Malvo had been molded into a killer by the charismatic Muhammad. Cooley said Malvo came to regard the Muhammad as a father figure and was susceptible to older man's influence because of his own father's absences and because his mother beat him and moved him constantly.
"Children are not born evil. When they commit evil acts, you can almost always trace the acts to the evil that has been performed against them," Cooley said.
Prosecutors had argued that death was the only appropriate sentence for Malvo, rejecting the suggestion that Malvo was less responsible for his crimes because he had come under the influence of Muhammad.
"They were an unholy team, as vicious as brutal and as uncaring as you can be," Horan said. "You can talk about John Muhammad all you want. Maybe it was his plan. Maybe it was his idea. But the evidence stamps this defendant as the shooter. ... He did it. Not John Muhammad."
The jury consisted of eight women and four men, eight whites and four blacks. The foreman was a 41-year-old minister, and four others had occupations connected to education. Two were homemakers.