Following reports that the bottles of pills found in Prince's estate contain fentanyl, a powerful type of opioid, an expert said the legendary musician may have used counterfeit drugs containing the ingredient prior to his death in April.

Speaking to People, Ben Levinson, an addiction expert and founder of Origins Behavior Healthcare, reportedly said that mislabeling bottles of pills is common in the trade of illegal prescription drugs. Levinson also said that these are considered illegal since they did not go through testing by the FDA. He added that many “extremely qualified pharmacists” have said that they had a hard time distinguishing which antibiotics are purely antibiotics and which ones were fentanyl disguised as antibiotics.

Levinson also maintains that there is a possibility that Prince knew what pills he was taking and mislabeling the bottles of pills in his house was a way to keep them safe in case he gets searched. He added that if the drugs, which were labeled Watson 385 – a lower grade of opiate – were from the usual drugstores people frequent, “they'd be shutting down the whole system.”

The authorities have yet to learn how the “Purple Rain” singer got a hold of the drugs.

An official involved in the investigation of Prince's death told the Associated Press that Vitamin C and aspirin bottles found in Paisley Park actually contained fentanyl, which is 50 times more potent than heroin. The bottles were found in a suitcase and a few bags, one of which was carried often by the legendary singer.

The “Nothing Compares 2 U” singer tested negative for the drug before he died, suggesting that the night he overdosed was the first time he took the pill.

Prince was found lifeless in an elevator in his home in Chanhassen, Minnesota on April 21, according to CNN. The musician was 58.