An investigation into George Michael's death will continue, as no results were obtained in the first autopsy.
The Thames Valley Police revealed the news in a statement Friday.
"A post mortem examination was carried out yesterday as part of the investigation into the death of George Michael," the statement said. "The cause of death is inconclusive and further tests will now be carried out. The results of these tests are unlikely to be known for several weeks. Thames Valley Police will prepare a file for the Oxfordshire Coroner. Mr. Michael's death is still being treated as unexplained but not suspicious."
Michael's rep had said earlier this week the singer died of heart failure and passed away "peacefully." Investigators later told E! News there were no suspicious circumstances surrounding Michael's death.
The famed singer and '80s rock and pop icon died on Christmas Day at age 53. He was found lifeless in bed at the home he shared with boyfriend Fadi Fawaz.
"ITs a xmas i will never forget finding your partner dead peacefully in bed first thing in the morning.." he tweeted. "I will never stop missing you xx."
Michael received several tributes from fellow music artists, including Coldplay's Chris Martin and longtime friend Elton John.
Martin performed Michael's former band Wham!'s 1986 hit "Last Christmas" at a homeless shelter last week. John honored his late friend by opening his Las Vegas concert Wednesday with "Don't Let the Sun Go Down on Me." He and Michael released a hit duet of the ballad in 1992. John told the crowd he wished Michael was there to sing the song with him.
“As a human being he was one of the kindest, sweetest, most generous people I've ever met," he added.