An early autopsy of George Michael was found to be “inconclusive” according to the Thames Valley Police. As the New York Times reports, a post-mortem examination was conducted yesterday, but did not yield any definitive results for a cause of death. The Thames Valley Police, who are responsible for the investigation into Michael’s passing on Christmas Day, released the statement below regarding the autopsy.

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. Mr. Michael’s death is still being treated as unexplained but not suspicious.

There are no details on the additional testing as of yet. Michael’s boyfriend, Fadi Fawaz, found the singer dead in bed in his Goring-on-Thames. Fawaz recalled to the Daily Telegraph, “We were supposed to be going for Christmas lunch. I went round there to wake him up and he was just gone, lying peacefully in bed. We don’t know what happened yet.”

Some speculate that the British pop star’s death could be drug related. Many friends and associates have noted that Michael had a long history of drug use and partying. In 2007, he was sentenced to community service and barred from driving for two years after he fell asleep at the wheel under the influence of drugs. In 2008, he was arrested in London on suspicion of the possession and use of crack cocaine. Michael Lippman, Michael’s manager, said that the Wham! singer, who had struggled with drugs and depression for years, died from heart failure, but that was not confirmed by the autopsy. Most recently, in 2015, Michael denied a serious battle with drug addiction in a statement issued through his publicists in response to an article published in British tabloid The Sun.

Mr. Michael, 53, was found dead in bed on Christmas Day by his boyfriend, Fadi Fawaz, at the singer’s home in the village of Goring-On-Thames.