A post-mortem into the death of iconic singer George Michael was inconclusive, the Thames Valley Police said on Friday. Further tests will be done, The Guardian reported them as saying. The tests will likely take weeks. Police had said that Michael’s death was “unexplained but not suspicious”.

The 53-year-old had died on Christmas day in his home in Oxfordshire, England. His manager Michael Lippmann had claimed the cause of death was heart failure. Michael’s publicist had said, “The family ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage.”

Michael’s partner Fadi Fawaz had said he had found him dead when he went to wake him for Christmas lunch.

Born Gergios Kyriacos Panayiotou in London in 1963, Michael formed Wham! in 1981 with Andrew Ridgeley. Michael was 19 when the duo’s first single “Young Guns (Go For It!)” released and became a smash hit in the United Kingdom. Soon after, he became a teen idol and went on to make many more successful albums until 1986 when Wham! announced their split.

His solo offerings, such as “I Want Your Sex”, “Faith”, “Father Figure” and “Careless Whisper”, were all No. 1 hits in the United States. Producer and songwriter Naughty Boy and Michael had been working on a new album before he died, BBC reported.

Michael had several run-ins with the law. In 1998, he was arrested for “engaging in a lewd act” in a public restroom in Beverly Hills, California. In 2006, he was arrested for possession of drugs in London, the first of the many such run-ins he had later in the decade. His sexual orientation was the subject of great deal of speculation, until in 1998 when Michael came out as gay.

Michael is among several other iconic musicians who died in 2016, including David Bowie, Prince and Leonard Cohen.