Singer-songwriter George Michael, who sold tens of millions of albums as a member of the duo Wham! and on his own, was found dead on Sunday at his home in Oxfordshire. England. Police are describing the death as "unexplained but not suspicious". He was 53. A police statement said: "Thames Valley Police were called to a property in Goring-on-Thames shortly before 2 p.m. Christmas Day. Sadly, a 53-year-old man was confirmed deceased at the scene. At this stage the death is being treated as unexplained but not suspicious." Michael's manager, Michael Lippman, told The Hollywood Reporter that he had died of heart failure "in bed, lying peacefully." "It is with great sadness that we can confirm our beloved son, brother and friend George passed away peacefully at home over the Christmas period," his publicist Connie Filippello said in a statement. "The family would ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage," the statement further reads, reports nytimes.com. Michael has sold more than 80 million records worldwide in a career spanning four decades. He was one of pop's reigning stars in the 1980s and '90s and some of his popular singles includes "Wake Me Up Before You Go-Go" with Wham!. Later he released a pop album in 1987 titled "Faith." He won a Grammy Award in 1988 for "I Knew You Were Waiting (for Me)," a duet with Aretha Franklin, and "Faith" won the Grammy for album of the year.