Feb 22, 2010 3:09 pm US/Eastern

A Maryland woman was convicted Monday of murdering two of her adopted daughters, whose bodies were found in a freezer in the woman's home.

Renee Bowman, 44, was found guilty of two first-degree murder charges in the deaths of the young girls. Their bodies were found in a freezer in her Lusby home in September 2008.

Bowman's lawyer argued the killings weren't premeditated and suggested jurors should convict her of lesser second-degree murder charges. However, prosecutors argued Bowman deliberately smothered the children.

She had already pleaded guilty in Calvert County to abusing the surviving girl, also adopted, and has been sentenced to 25 years in prison in that case.

Authorities say the older girls, Jasmine and Minnet, were killed in Rockville more than three years ago, but they don't know exactly when. Minnet would have been 12 now, and Jasmine would have turned 11 on Tuesday.

Bowman moved from Rockville to Charles County and later to Lusby. Prosecutors say she brought a large freezer containing the bodies of Jasmine and Minnet with her each time she moved.

The 9-year-old surviving daughter, clutching a Valentine's Day teddy bear, testified last week against Bowman, whom she called her "ex-mother." When she was 7, the girl was found half-naked and covered in blood after escaping from the Bowman home. Afterward, authorities found the frozen bodies.

The girl said she and her sisters were kept in a locked room of their Rockville home.

"There was a bucket where we went to the bathroom because we weren't allowed out of the room," she said.

The girl said Bowman repeatedly beat her and her sisters with a baseball bat and a shoe.

Montgomery County State's Attorney John McCarthy asked her on what part of her body she was beaten the worst. Asked to demonstrate on the bear, she pointed to its backside and its crotch.

When McCarthy asked who hit her, she replied, "ex-mother," and never looked at Bowman, who was seated a few yards away.

Bowman continued to receive subsidies for all three children from the District of Columbia, where the girls were adopted. The subsidies are given to parents who adopt special-needs children from foster care.