Tests have revealed iconic musician Prince died as a result of an opioid overdose, according to authorities. The 57-year star was found unresponsive in a lift at his home Paisley Park home in Minneapolis on 21 April before later being pronounced dead at the scene.

A law enforcement official has now told the Associated Press on condition of anonymity that Prince died after overdosing on the powerful painkiller. The singer was hospitalised just six days before his death in what is believed to be a separate overdose.

Prince was found unconscious on a plane as he made his way back from a gig in Atlanta. He was believed to have been administered a shot of Narcan, an antidote used in suspected opioid overdoses.

An autopsy was conducted the day after Prince's death but the official results have not been released. Investigators are already looking into whether Prince's death was due to an accidental overdose and who was the doctor who may have been prescribing him the medication.

At least two doctors' names have come up in the death investigation, including Dr Michael Todd Schulenberg, who saw Prince on 7 April and 20 April - the day before his death - according to a warrant. Schulenberg admitted prescribing medications for the singer which were not specified in a search warrant for the Minnesota hospital that employed Schulenberg at the time.

A second doctor, Dr Howard Kornfeld, a California addiction specialist, was also asked by Prince's representatives to help the singer the day before he died. Kornfield's son Andrew, who is not a doctor, was sent to Prince's home instead on an overnight flight and was one of the first people to find Prince unresponsive the next morning.

Andrew Kornfeld was carrying buprenorphine, a medication that can be used to treat opioid addiction, claiming he was intending to give the medication to a Minnesota doctor who was seeing Prince the following day. Mr Kornfeld's lawyer, William Mauzy, has refused to disclose the name of the Minnesotan doctor. Schulenberg is not authorised to prescribe the drug buprenorphine.

Despite the famous Jehovah's Witness being thought of having a clean lifestyle, rumours about Prince's addiction to painkillers in later life began to circulate following his death.