The judge overseeing the Prince estate case has authorised genetic testing on a sample of his blood in case it’s necessary to determine who’s entitled to shares of the estate.

Prince died without a will, according to his sister Tyka Nelson, and the estate is expected to be split between her and their five half siblings.  Bremer Trust, the musician’s bank, has been appointed special administrator to oversee the estate for now.

Prince's sister Tyka Nelson said the singer left no will (Leila Navidi/AP/PAPrince’s sister Tyka Nelson said the singer left no will (Leila Navidi/AP/PA)

Carver County District Judge Kevin Eide on Friday granted a request by the Bremer Trust to hire The DNA Diagnostics Centre to perform genetic testing on a blood sample now held by the medical examiner’s office that conducted the autopsy on Prince.

Prince died April 21 at his home in suburban Minneapolis. The cause remains under investigation.

In his order, the judge says he’s “recognising that parentage issues might arise” in the administration of Prince’s estate. He’s authorised the medical examiner to release the blood sample to the testing laboratory.

Prince.Prince died on April 21 at his home in Minnesota (Chris Carlson/AP)

The news comes as a law enforcement official said investigators want to interview a California doctor and his son about a prescription drug the son brought for Prince before the singer was found collapsed in an elevator at his Minnesota home.

The official told The Associated Press that investigators also want to know if Dr Howard Kornfeld and son Andrew Kornfeld had a longer-term medical relationship with Prince. Neither is accused of wrongdoing.

The law enforcement official had been briefed on the investigation and spoke on condition of anonymity because he wasn’t authorised to speak to the media.

Dr Harold Kornfeld's attorney William Mauzy (Jim Mone/AP/PA)Dr Harold Kornfeld’s attorney William Mauzy (Jim Mone/AP/PA)

The Kornfelds’ attorney, William Mauzy, said Prince’s staff called Howard Kornfeld on April 20. He sent his son on an overnight flight with the drug buprenorphine, used to treat opioid dependence.

Andrew Kornfeld found Prince unresponsive and did not administer the drug.