Port Huron police continue to investigation into what appears to be a possible heroin overdose. According to reports, a 27-year-old man was dropped off at Port Huron Hospital about 2:30 p.m. Friday of last week. The man, a St. Clair County resident, was unresponsive. Authorities believe he had overdosed on heroin. He is in the hospital’s intensive care unit. It is believed that the overdose happened in the city of Port Huron. Two Port Huron residents, a 32-year-old white male and a 33-year-old white female, were taken into custody by Port Huron police in connection with the incident.