By Sara Sidner and Rosalina Nieves

CNN

(CNN) -- Opioid painkillers were found in several places in Paisley Park in the days following Prince's death last year, court documents released Monday showed.

According to a search warrant issued April 21, 2016, the day Prince was found dead in his home in Chanhassen, Minnesota, investigators found several pills labeled "Watson 853" -- hydrocodone-acetaminophen -- in different bottles in the residence. Also according to the search warrant, investigators were told by witnesses that Prince "recently had a history of going through withdrawals which are believed to be the result of abuse of prescription medication."

Prince, whose full name was Prince Rogers Nelson, died at the age of 57. The medical examiner's office said his death was the result of an accidental overdose of the opioid fentanyl.

Last August, the Minneapolis Star Tribune quoted a source with knowledge of the investigation as saying that pills seized inside the compound by investigators were labeled as hydrocodone but actually contained fentanyl.

The revelation gives more insight into what may have caused Prince's overdose. There are two likely possibilities: Either a pharmaceutical manufacturer mislabeled the pills, or the pills were illegally manufactured and obtained illegally.

However, according to the Star Tribune, investigators are working under the theory that the pop star did not know the pills contained fentanyl.

CNN's Alanne Orjoux contributed to this report.