CASTLE ROCK, Colo. (CBS4) – A jury on Tuesday convicted a woman in Castle Rock of murdering her two young children.

Kelli Murphy, a mother of two, was arrested last May after investigators found the bodies of 9-year-old Liam and 6-year-old Madigan in their beds. Prosecutors say Murphy killed her children to get back at her ex-husband after a divorce.

Jurors needed only an hour and a half to convict Murphy. She was immediately sentenced to life without parole.

The guilty verdict came on the same day Liam would have turned 11.

“The system has its limitations. We can tell a defendant and hold a defendant accountable for their actions, but we can never bring Liam and Maddy back,” Senior Deputy District Attorney Jay Williford said.

The defense did not have a comment. They argued that Murphy was attempting to kill herself while intoxicated on alcohol and drugs, blacked out and woke up to her children suffocated, not remembering anything.

Prosecutors argued that Murphy is a control-bent woman who wanted custody and divorce terms all her way or nothing at all.

“She wanted it on her terms, her way, or no other way,” Williford said. “And she would take nothing less than what she wanted.”

(credit: CBS)

Murphy’s former father-in-law walked from the courtroom emotionless after the verdict was read. Liam and Madigan’s father, Eric Murphy, was not in court. He now lives in Washington. Other family members appeared on his behalf. They released a statement after the verdict.

“This is a sad day for us. We would have preferred to be celebrating Liam’s 11th birthday today,” the statement said. “Although nothing can make up for the loss of Liam and Madigan, or fill the void that is left by their absence, we are thankful that this chapter is now over.”