VIRGINIA BEACH, Va. - Declaring their love for him "no matter what," John Allen Muhammad's three young children became part of the grim testimony yesterday on whether he should be sentenced to death for killings that still have no clear explanation.

"Why did you do all those shooting?" Muhammad's youngest daughter, 10-year-old Taalibah, wrote in a letter read aloud in court yesterday by her mother, Mildred Muhammad.

It was a bitter child-custody battle with Mildred Muhammad that prosecutors say sent the former soldier into a rage and possibly sparked last year's sniper rampage that spread terror in the Washington region.

Mildred Muhammad also told the jury yesterday that Taalibah recently told her, "Mommy, if Daddy gets out [of prison], then that means that he will kill you, and I don't want to live the rest of my life without my mommy."

The fear is not without foundation, Taalibah's mother said. One day in early 2000 when their marriage was falling apart, she said, John Muhammad took her into the garage of her Tacoma, Wash., home and told her, "Just know this: You have become my enemy and as my enemy, I will kill you."

Mildred Muhammad testified against her ex-husband yesterday as one of the state's final witnesses in its case for the death penalty. Jurors, who convicted the Persian Gulf war veteran of two counts of capital murder Monday, must choose a sentence of life in prison without parole or execution.

They are expected to begin deliberations late today or tomorrow.

The courtroom meeting between Mildred and John Muhammad was the first time they had seen each other since a Sept. 4, 2001, court hearing, when Mildred Muhammad won custody of the children. Prosecutors say that date marked the beginning of the convicted sniper's slow descent into violence.

Mildred Muhammad said the children's letters - delivered in envelopes bearing hand-drawn hearts - were the children's idea, and she did not tell them what to write.

Even witnesses for the defense, which began its case yesterday afternoon, said they noticed a change in Muhammad at that time. Mary Marez, a Tacoma nurse who became friends with Muhammad in 1995 and later had an intimate relationship with him, said he was desperate to find them and make sure they were all right.

"John became withdrawn, and he would sit and just stare out the window," Marez said. "He just wasn't himself. He missed them terribly."

The children have not seen their father since the 2001 court date, and their letters to him were both updates on their lives and assurances of their love. The children live with their mother in Clinton, Md., where they have followed the news of their father's trial. Mildred said she told them not to judge their father until the jury reached a verdict.

In the letter from the eldest of the three, 13-year-old John Jr. writes that he is playing full-contact football and is in a school play. He says he has more female friends than male friends, as his father had predicted. John Jr. closes his letter: "Dad, I love you so much and nothing will ever change that ever."

In her letter, 11-year-old Salena says she plays the violin, makes good grades and is in the school chorus and patrol. She writes, "I pray that I can write you a letter again. I love you very much and I always will."

Taalibah, who is 10, asks her father four questions in her letter. Besides asking why he did the shootings, she asks whether he did most of them. She asks about Muhammad's alleged accomplice, Lee Boyd Malvo, and a phrase written on a tarot card left outside the Bowie middle school where a boy was shot.

"And did you till [sic] Lee to say 'Call me God'?" she writes. Taalibah also appears to have made a heartbreaking calculation - the years until she turns 16 and would be able to visit her father in prison:

"It will be a long time until I visit you. And I love you Daddy and I always will. NO MATTER WHAT!!!!!"

Mildred Muhammad said that John Jr. told her, "Mom, if Dad takes you out, then I'm going to have to take him out." That comment was made outside the jury's presence, and the judge ruled that jurors would not be allowed to hear it.

Through much of the three hours his former wife spent on the stand, John Allen Muhammad sat with a blank stare, his right elbow resting on the defense table and his right hand supporting his chin. At one point, he flipped through family photos of him with his children - photos his lawyers later showed the jury.

Mildred and John Muhammad married in 1988 and separated in 1999. On March 27, 2000, John Muhammad picked up the two girls from school and came to Mildred's house to get John Jr. He said he was taking them shopping. Instead, he took them to the Caribbean island of Antigua, traveling under aliases.

He returned with the children to Washington state in August 2001; they were soon seized by authorities and turned over to the mother. After the custody hearing, Mildred Muhammad said, she saw him in the corridor.

"I looked to my right and saw John coming down the hall, and I ran down the hall away from him because of the way he was coming toward me," she said. "For me, it was hostile. I knew he was coming for me."

That night, Mildred Muhammad boarded a plane for Baltimore with her three children. Her attorney had advised her to leave Washington as soon as she could. "She said based on John's behavior in court, I needed to leave for fear that he may find me and kill me," she testified.

Defense attorneys presented six witnesses who knew their client in Washington state. They testified that he was a considerate and polite person who loved his children. They said that even when customers of his auto repair business couldn't pay their bills, he worked on their cars because he wanted them to be safe.

The lengthiest testimony came from Marez, a single mother who said she had an affair with Muhammad in the late 1990s. She said he was a wonderful cook and a gifted mechanic who had dreams of owning his own restaurant and opening a gym.

"John is a very considerate person and just the strongest, most gentlest person I've ever known," said Marez, 45. "I feel that his life will always have value. I know he's a person with so much to give."

She choked up with tears during her testimony, and jurors quickly passed over to the witness stand a box of tissues they had been using earlier in the day. Several jurors had cried and covered their eyes during the emotional testimony of Larry Meyers, the oldest brother of sniper victim Dean H. Meyers, 53.

A civil engineer, Dean Meyers survived a bullet in the arm fired by a Viet Cong sniper in Vietnam only to be killed years later by another sniper at a gas station north of Manassas, Va. His death was one of 10 sniper killings last October that authorities have linked to Muhammad and Malvo.

Larry Meyers said his brother was a humble, frugal person who never owned a CD player or a large television but gave thousands of dollars to charities and sponsored children in Africa for 20 years. Meyers told of how he had to break the news to his parents of their son's death.

He said his mother had dementia and did not fully understand. She died Easter Sunday this year - a death that Meyers said was accelerated by her son's murder. Meyers said his father broke down as his son delivered the news of the murder.

"Losing someone like that causes a void which can never really be replaced," Meyers said. He talked of how two years ago the four Meyers brothers decided to try to visit as many baseball parks as they could in the coming years. So in 2001, they took the train to New York to catch a game at Yankee Stadium. And in 2002, they went to Boston to see Fenway Park.

"He was my brother, and I think he was my best friend," Meyers said through tears. He also read a reflection he wrote recently, addressed to his brother: "We missed you last Thanksgiving and at Christmas, too. Mom left us Easter morning. She now lies near you. Perhaps you've already met up there. This year we didn't have a Labor Day picnic. And no trip was planned."