An Arlington County jury recommended yesterday that a former Marine who killed his wife, his 5-year-old daughter and his girlfriend in a motel room in January 2002 be spared execution but spend the rest of his life in prison.

Zachary Cooper, 24, was convicted of capital murder Wednesday. The jury deliberated about six hours over two days before deciding on a life sentence, for which there is no parole. Arlington Circuit Court Judge Joanne F. Alper is scheduled to impose the sentence March 3.

Arlington Commonwealth's Attorney Richard E. Trodden said he is satisfied with the jury's decision. "We feel the jury had all the evidence and they considered it very thoroughly," Trodden said. "The fact they gave him life is perfectly acceptable to us."

Mark Thrash, one of Cooper's attorneys, said he was pleased the jury did not recommend death.

Prosecutors said Cooper decided to kill his wife, Maya, 21, and his girlfriend, Marie Gault, 20, so he could pursue a romantic relationship with a third woman, whom he met at the Fort Knox, Ky., Army base where he was stationed.

On Jan. 20, 2002, while visiting family in Virginia, Cooper arranged for his wife, Gault and his daughter, Dessire, to come to the Cherry Blossom Travelodge in Arlington, prosecutors said. They said he shot Maya Cooper and Dessire and then shot and stabbed Gault in a third-floor room.

During the 10-day trial, prosecutors said that Cooper's relationship with his wife had become strained and that he had promised to marry Gault and bought her an engagement ring in November 2001. But then Cooper decided that the only woman he wanted was Cartrice Mullins, who lived next door.

Cooper admitted during the trial that he killed Gault but said it was only after Gault shot Maya Cooper and Dessire.

Cooper's attorneys said they are considering an appeal.

On Thursday, Maya Cooper's grandmother, Barbara McDaniel, told jurors that the couple's 3-year-old son, Xaviour, is struggling with his mother's death and is undergoing counseling. McDaniel, who cares for the boy, said he asks for his mother every day.

"He cries for his mom," McDaniel said. "He thinks his mommy brought him to my house and left him. You don't know how much that hurts."

Gault's sister, Tasha Burzynski of Woodbridge, testified that she is raising Gault's daughter, Keilani, who was in the hotel room when her mother was killed. Keilani was not injured.

Burzynski told jurors that her sister's death has meant the loss of her best friend and confidante. They relied on each other because their parents are in prison, she said.

"We didn't go anywhere without being together," Burzynski said.

Cooper was convicted of two counts of capital murder in the death of Dessire. Virginia law allows a capital murder charge when the victim is younger than 14 or part of a multiple homicide. He was convicted of two additional counts of capital murder in the slayings of his wife and Gault. The jury recommended a life sentence for each charge plus 13 years for three weapons violations.

Zachary Cooper, 24, of Fort Knox, planned to start a new life with another woman, prosecutors said.