A post-mortem examination on the body of late pop icon George Michael, who died on Christmas Day after a chart-topping career and years of drug-taking, has proved "inconclusive", police said on Friday.
"The cause of death is inconclusive and further tests will now be carried out. The result of these tests are unlikely to be known for several weeks," according to a police statement.
The post-mortem was carried out on Thursday.
The police said earlier they were treating his death as "unexplained but not suspicious".
Michael was found "lying peacefully" in bed by his partner Fadi Fawaz at his home in the village of Goring on the River Thames west of London.
His manager Michael Lippman told Billboard magazine that the cause of death appeared to be heart failure.
Tributes have poured in from heartbroken fans leaving flowers, candles and emotional messages outside his homes in Goring and London over the past few days.
Michael notched up police cautions for cannabis and crack cocaine possession in his final years and in 2010 was sentenced to eight weeks in jail after crashing his 4x4 into a London shop while under the influence of cannabis and prescription medication.
In 2011, he spent several weeks in hospital in Vienna after contracting pneumonia, later saying he had been close to death.