Shortly after his discharge, Heidnik became a licensed practical nurse, and enrolled at the University of Pennsylvania, only to drop out after one semester. He worked at a Veterans Administration hospital in Coatesville, but was fired for poor attendance and rude behavior towards patients. From August 1962 until his arrest in March 1987, Heidnik spent time in and out of psychiatric hospitals, and had attempted suicide at least 13 times. In 1970, his mother, Ellen, who had been diagnosed with bone cancer and was suffering the effects of alcoholism, committed suicide by drinking mercuric chloride. His brother, Terry, also spent time in mental institutions, and attempted suicide multiple times.