The doctor who prescribed pills for Prince has been sued by the singer's relatives, who charge in court documents that the physician failed to properly diagnose and treat an opioid addiction, the Star Tribune of Minneapolis reported.

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A wrongful-death lawsuit accuses Michael Schulenberg and his employer, North Memorial Health Care, of administering painkillers that were not needed in the days preceding Prince’s death, according to court documents.

“He failed to appropriately evaluate, diagnose, treat and counsel Prince for his recognizable opioid addiction, and further failed to take appropriate and reasonable steps to prevent the foreseeably fatal result of that addiction,” the lawsuit says of Schulenberg, a family physician. “These departures from the standard of acceptable medical practice had a substantial part in bringing about Prince’s death.”

Paul C. Peterson, a Minneapolis attorney representing Schulenberg, said he believes the case lacks merit.

"We understand this situation has been difficult on everyone close to Mr. [Prince Rogers] Nelson and his fans across the globe," he said in a written statement to the Star Tribune. "Be that as it may, Dr. Schulenberg stands behind the care that Mr. Nelson received. We intend to defend this case."

Prince, 57, died April 21, 2016, of an accidental fentanyl overdose, the Star Tribune reported.

Federal search warrants issued after Prince’s death revealed that Schulenberg admitted to writing prescriptions for Prince’s longtime bodyguard and associate, Kirk Johnson, knowing they were actually for the singer, the newspaper reported.

In 2016, Prince’s heirs sued the Moline, Illinois, hospital that treated him for an opiate overdose less than a week before his death.