Several pills recovered at pop star Prince’s estate in Paisley Park after his death were counterfeit drugs which contained the powerful opioid fentanyl, officials have said.

Many of the pills were said to have been found inside aspirin and vitamin bottles tucked in a suitcase, as well as in duffel bags and in a dressing room.

Post-mortem test results released in June show Prince died on April 21 of a fentanyl overdose.

Records show Prince had no prescription for any controlled substances in the state of Minnesota in the 12 months before he died at the age of 57.

Authorities are still investigating how Prince obtained the drugs.