A 20-year-old man died last weekend at a home in the 4200 block of West Mercer Way. He was a 2008 graduate of Mercer Island High School and lived in Bellevue. Police were called to the scene at 2:20 p.m., Sunday. The time of death has yet to be determined, but police believe that he may have died before Sunday afternoon. He had been reported missing by a family member. The unexplained death is being investigated by the King County Medical Examiners office. It is not yet known if alcohol and or drugs are involved in the death. Toxicology and other reports are pending. According to Mercer Island Police Commander Leslie Burns, Island police are talking with friends, acquaintances and anyone who had last seen the man.