A South Carolina mother was handed down a 20-year prison sentence on Friday after she was found guilty of homicide by child abuse, involuntary manslaughter, and unlawful conduct toward a child. Stephanie Greene, 39, was facing a potential life sentence for the breastfeeding overdose of her child caused by a lethal dose of morphine she delivered to her 6-week-old daughter, Alexis, via breast milk.

Back on Nov. 13, 2010, Alexis was found dead in her parents’ bed with no identifying marks to suggest a cause of death. Police arriving on the scene said Greene had trouble walking, slurred her words, and displayed unfocused eyes, WYFF4 reported. During a toxicology report, morphine along with the benzodiazepine drug Klonopin were found in the infant’s blood stream. A pathologist involved with the case said the amount of morphine found in Alexis’ system was enough to cause deadly results for an adult.

Prosecuting attorney, Barry Barnette said medical records showed that Greene, a nurse with a B.S.N degree, had kept her pregnancy a secret from her primary physicians so they would keep prescribing her medication for chronic pain she suffers from due to an automobile accident 10 years back. She also kept her addiction to painkillers hidden from the gynecologist she met with for prenatal care.

Those involved with the case say this is the first time a mother has been prosecuted in the United States for killing her child through drug-tainted breast milk. Greene is expected to serve 16 years of her prison sentence before she becomes eligible for parole, The Washington Post reported. Greene’s attorney, Rauch Wise, said his client needed painkillers to function with the chronic pain she suffered from in addition to fibromyalgia. Wise expects Greene to appeal her conviction saying there is little scientific evidence to prove a fatal dose of morphine can pass from mother to child through breastfeeding.