Authorities revealed on Friday that further tests will be needed.
George Michael's official cause of death remains unknown.
A post-mortem examination into the singer's cause of death was found to be "inconclusive," according to a statement released by the Thames Valley Police on Friday.
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"The cause of death is inconclusive and further tests will now be carried out," the statement read, citing that the examination took place on Thursday. "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," the statement concluded.
The GRAMMY award-winning singer died in his sleep at his country home in London, England, on Dec. 25. In a statement released shortly after his death, his manager, Michael Lippman, said he believed the singer suffered heart failure.
"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 rep told ET. "The family would ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage."
For more on the beloved pop icon, watch the video below.