ALLENTOWN (AP) - A woman convicted as a teenager in the murder of her mother 6½ years ago has returned to an eastern Pennsylvania courtroom seeking a new trial.

Now-20-year-old Jamie Silvonek was sentenced to 35 years to life after pleading guilty in Lehigh County to first-degree murder and other charges in the slaying in March 2015, when she was 14 years old.

Caleb Barnes of El Paso, Texas, a Fort Meade, Maryland soldier, was convicted of first-degree murder and sentenced to life without parole plus 22 to 44 years. Silvonek testified that she plotted the murder of 54-year-old Cheryl Silvonek in Upper Macungie Township and urged Barnes in texts to carry it out.

Authorities said Barnes stabbed the victim in her car in the driveway after Barnes, Cheryl Silvonek and Jamie Silvonek returned home from a concert. Authorities said the defendants then buried the victim’s body and submerged her car in a South Whitehall Township pond. They were arrested within hours of the slaying.

Prosecutors said the woman had threatened to report Barnes, then 21, to police for having sex with her underage daughter. Jurors rejected Barnes’ argument at trial that the girl killed her mother and he only helped dispose of the body later because she said she was pregnant.

Silvonek previously lost her appeal to have her case sent back to juvenile court on the grounds that she has mental health issues. She now seeks a new trial, arguing that her previous attorney was ineffective and that her guilty plea in February 2016 was not knowing and voluntary.

Her previous attorney has defended his representation, saying he called three expert witnesses seeking to have her tried as a juvenile, but once the judge ruled against that his options were limited.