PITTSBURGH – A Pennsylvania woman who drowned her two youngest sons in their bathtub because she felt that would enable her to be a better mother to their older brother was sentenced to 30 to 80 years in prison.

An Allegheny County judge called the sentence imposed Wednesday on 44-year-old Laurel Schlemmer, who was found guilty but mentally ill of third-degree murder in March, a de-facto life term given her age.

She’ll begin her sentence in a state mental hospital and then will be moved to prison if doctors ever deem her cured.

The McCandless woman’s attorney had argued her diminished mental capacity kept her from forming the intent to kill her sons, 6-year-old Daniel and 3-year-old Luke, in April 2014.

Schlemmer has told police she killed the boys so she could be a better mother to their elder brother, who was 7 years old at the time.

Psychiatrists for the prosecution and defense testified in March that Schlemmer became concerned and even obsessed with the idea that her two youngest sons were autistic and would never grow up normally, even though a battery of tests she put them through showed they did not have a disability.

Schlemmer met her husband, Mark, on a Christian singles online dating site. She has said she felt “pressured” to have more children as her husband opted not to use birth control for religious reasons.

Schlemmer also had three miscarriages and came to feel her younger sons, especially Daniel, were “foreign” to her and her husband and not as easy to raise as their oldest boy, according to Dr. Bruce Wright, the prosecution’s expert.

Schlemmer drowned the younger boys after taking her oldest son to a school bus stop on April 1, 2014.

She had acknowledged trying to kill Luke and Daniel in April 2013 by tying their hands and feet with twine and backing over them with her car three times, but then claimed it was an accident. Police and social workers also determined it was an accident. Schlemmer told her husband days before the drownings that she wanted to confess to that crime, but he talked her out of it, prosecutors said.