A South Carolina woman was sentenced to 20 years in prison Friday for killing her infant with drug-tainted breast milk.

Stephanie Greene, 39, was sentenced after killing her 46-day-old baby with a morphine overdose from her breast milk, according to American Live Wire.

Greene was found guilty of involuntary manslaughter, unlawful conduct toward a child and homicide by child abuse. Greene will be forced to serve 80 percent of her prison sentence before being deemed eligible for parole.

In November 2010, Greene's infant daughter, Alexis, was found dead in her parent's bed.

According to a pathologist who testified in the case, the infant had high levels of morphine in her system at the time she was found dead.

Prosecutors believe Greene hid her pregnancy from doctors so she could continue receiving prescription pain killers. She also did not tell doctors that she was breast feeding her child.

Morphine from the pain killers seeped into Greene's breast milk, then entered the baby's bloodstream, leading to her death.

Greene's defense attorney claims that the prosecution did not prove how the baby received the high level of morphine, or how the high level of painkillers were able to contaminate Greene's breast milk.

Greene and her lawyer, Rauch Wise, are expected to file an appeal in the upcoming months. Wise said that Greene "already suffered an immeasurable loss with the death of her child and shouldn't have to face prison time."

Greene has not commented publicly about the case, or about the death of her child. Her family has stayed out of the public eye, and has remained silent about the case.