The letter wasn't shown to the jury in Malvo's capital murder trial yesterday but was brought up by Muhammad's first wife, who testified that the note shows Malvo realized he was in trouble and needed someone to rescue him.
Williams testified that Malvo, who was introduced to her last summer as her ex-husband's 17-year-old son, wrote the letter to her niece. Malvo had befriended the girl, 17, and felt he could confide in her, she said.
Only one line of the letter has been publicly revealed. It reads, "I have a father who I know is going to have to kill me for a righteous society to prevail" and was introduced by defense lawyer Craig S. Cooley during a pretrial hearing.
Defense lawyers said they will try to introduce the entirety of the letter today, but it's likely prosecutors will object to that.
In opening statements, Cooley had contended that the sniper shootings - which left 10 dead and spread terror throughout Maryland and Virginia - were done because Muhammad ultimately wanted to kill Mildred Muhammad, his second wife.
Cooley said Muhammad, 42, also might have killed Malvo afterward to silence the only witness and to keep the murderous plot a secret from the couple's children.
Muhammad had gone to Baton Rouge, La., in 2002 to visit his family with Malvo in tow. Carol Williams had not seen Muhammad in nine years. No one questioned whether the impeccably mannered 17-year-old really was Muhammad's son.
"Everyone just fell in love with him because he was nice," Carol Williams said, explaining that the youth always offered to help out and read to the younger children.
It was only after Muhammad and Malvo ended their visit of five to seven days that the letter surfaced, leading Carol Williams and three women in Muhammad's family to gather and discuss it.
"I know how I felt when my child was gone ... and he came back a totally different child," Carol Williams said.
"He is a manipulator," Lindbergh Williams, the son of Williams and Muhammad, told jurors.
He described his father as someone who tries to "get inside your head" and "take advantage of your weakness."
The 21-year-old said he spoke from painful experience. When he was 11, he was sent for a summerlong visit with Muhammad and his new family in Tacoma, Wash.
Over the weeks, he said, his father drummed up a story of abuse by his mother until he believed it and was amenable to living with his father.
Despite combative cross-examination by Fairfax County Commonwealth's Attorney Robert F. Horan Jr., Lindbergh Williams stuck to his account.
"After a while I believed him," Lindbergh Williams said, later adding that his father "embedded this in my head."
Lindbergh Williams also said he didn't question it when his father introduced Malvo to him "as my brother," because "I know what kind of man my dad was."
Asked by defense lawyer Thomas Walsh if he loves his father, he replied, "Of course."
The defense has scheduled for Lindbergh and Carol Williams a return trip to give Lindbergh Williams an opportunity to visit his father in the Prince William County Detention Center.
Convicted of capital murder in the Oct. 9, 2002, fatal shooting of Gaithersburg engineer Dean H. Meyers at a gas station north of Manassas, Va., Muhammad, 42, was sentenced to death last week by a Virginia Beach jury.
Yesterday's appearance by Williams and her son on behalf of Malvo - neither testified in Muhammad's recent trial - marks the most powerful testimony the defense has placed before jurors so far.
It also marks the defense's shift away from Malvo's childhood in the Caribbean to trying to show that Muhammad changed him into a killer. Malvo is pleading not guilty by reason of insanity.
He is charged with two potential death-penalty murder counts in the fatal shooting of FBI analyst Linda Franklin, 47, who was felled Oct. 14, 2002, in the parking lot of a Home Depot store in a bustling shopping area of Fairfax County.
One count accuses Malvo of multiple murders within three years. The other, under Virginia's untested anti-terrorism law, accuses the Jamaican-born youth of scheming to extort $10 million from the government to end the shootings.
Each described the teen-ager as subservient to Muhammad.
Muhammad arrived at the shelter Aug. 16, 2001, with the three children he had abducted from his estranged second wife in Tacoma, Mildred Muhammad. Workers said he doted on the youngsters. But two weeks later, the children were gone, returned to their mother by child protective workers.
The nine woman, seven-man jury was not permitted to hear what the Rev. Ronald Lee Todd, the shelter's chaplain, said Malvo confided one night about his hesitancy to convert to the Muslim faith.
He said Malvo told him "my leader said to me ... we'd like to take over America. Malvo said, when I heard that, I was not so sure I wanted to be a part of that."
Outside the courtroom, Malvo's lawyers said their client has left the Muslim faith.
The relationship between Malvo and Muhammad was evident even at a Bellingham coffeehouse where the two played chess and had "an intense type of conversation," said Peter David, who worked at Stewart's Coffee House.
David also said that Malvo took lots of honey from a large jar to make sandwiches, which he found odd.
"I'd never seen anybody eat that much honey before," he said.