Pennsylvania is one of five states lacking a law to protect adults with intellectual and developmental disabilities, according to this article. It tells the story of Michael Ferrara, 25, who cannot identify who abused him, but suffered injuries in a February 2008 assault while living in a group home.
Michael's doctor said that the injuries indicated Michael was "subjected to choking and trauma to the head, face and neck".
Because no charges were filed, the person responsible is free to continue to work with vulnerable adults since there is no protection under the law for those between 18 and 59 living in private residences.
Related: An Assessment of the Need for an Adult Protective Services Program (pdf)