Lees said the baby died about four days after her parents, suffering from dehydration and starvation. Lees ruled her death a homicide because of neglect from her parents, WTAJ reported.
Police said they do not know who sold the drugs to the couple, but if the person is found, he or she could face charges of drug delivery resulting in death.
The couple's death was originally attributed to heroin overdoses before toxicology tests. Lees and Cambria County District Attorney Kelly Callihan said heroin was found in the house, WJAC reported in December.
Chambers also overdosed in November, but was revived with Narcan, WJAC reported.
Children and Youth Services checked on Summer's welfare on Dec. 7.