ST. JOHNSBURY, Vt. — A woman convicted along with her husband of killing a prep school teacher in 2012 after they decided “to get a girl” was sentenced Friday to life in prison without the possibility of parole.

Patricia Prue gave up a possible insanity defense a day earlier and changed her plea to guilty to aggravated murder in the disappearance and killing of St. Johnsbury Academy teacher Melissa Jenkins, who prosecutors say was lured to her death with a ruse about a broken down car.

Prue apologized to Jenkins’ family and said she wished she had gotten the mental health help she needed.

“I’m not sorry we were caught. I am sorry that it ever happened,” she said.

Prue’s lawyer, Brian Marsicovetere, used the sentencing hearing to call for more support for mental health services and early intervention, saying his client is severely mentally ill. He said she suffers from post-traumatic stress disorder, panic and personality disorders, and general anxiety.

But prosecutors said mental health was not the main issue in the case.

Caledonia County State’s Attorney Lisa Warren said the Prues spent months plotting the March 25, 2012, crime in order to fulfill a fantasy: Patricia Prue’s computer had been used to conduct online searches for “how to kidnap a girl,” the Prues stalked Jenkins, got a stun gun and bought a prepaid cellphone to call Jenkins to ask for help. The Prues lured the 32-year-old from her home, strangled and beat her and dumped her body in the Connecticut River, Warren said.

Jenkins, a single mother, was reported missing after her vehicle was found that night idling on a road with her 2-year-old son inside. Her body was found the next day.

Patricia Prue said she wanted to plead guilty so she could resume written contact with her husband, Allen Prue, who is serving a life sentence for first-degree murder.