BALTIMORE, July 28 (UPI) -- A Baltimore woman sentenced to 40 years in prison for abusing and killing a child she was caring for has asked a judge to overturn her conviction.

Satrina Roberts entered a guilty plea six years ago. Her lawyers now argue that she did not understand what she was doing when she pleaded guilty because of "mental health issues," low intelligence and heavy drinking, the Baltimore Sun reported.

Roberts became the legal guardian of Ciara Jobes because the girl's mother was terminally ill with AIDS. The girl, then 15, died in 2002.

When Ciara's body was found, investigators said she had hundreds of scars and weighed only 73 pounds.

Maryland made changes in laws governing legal guardianship after Ciara's death. Legal guardians must be evaluated for parental fitness, and judges who place children now have the power to inspect their homes after placement.

A hearing on Roberts' application for post-conviction relief was scheduled Wednesday afternoon.