An autopsy on Heath Ledger has proved inconclusive.

The New York medical examiner's office confirmed today that more tests will be needed to establish the cause of death.

Their spokesperson, Ellen Borakove, said it will take about 10 days to complete the investigation.

The 28-year-old Aussie actor was found dead in bed from an apparent overdose on Tuesday by his housekeeper and masseuse.

Police have said that bottles of prescription medicines were found lying nearby.

Ledger’s family have released a statement saying that they do not believe the star would take his own life.