Prince's family has filed a lawsuit against Dr. Michael Schulenberg—the physician who is accused of illegally prescribing an opioid to the late singer.

According to ABC News, the suit was filed Friday in Minnesota district court. The plaintiffs claim Dr. Schulenberg neglected to treat Prince’s opioid addiction prior to his fatal overdose in 2016. Toxicology reports later confirmed the singer’s system contained “exceedingly high” levels of fentanyl at the time of his death.

“[Dr. Schulenberg] 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 reads. “These departures from the standard of acceptable medical practice had a substantial part in bringing about Prince’s death.”

According to the Associated Press, Dr. Schulenberg allegedly provided Prince with oxycodone just days before his death; however, authorities say the doctor admitted to prescribing the drug under the name of Prince’s bodyguard to ensure privacy. The physician denied the allegations, and was never charged in the singer’s death.

Investigators failed to determine where Prince received the pill that ultimately killed him; however, Prince’s family insists the death could’ve been prevented had the doctor done his job.

“We understand this situation has been difficult on everyone close to Mr. Nelson [Prince] and his fans across the globe,” the doctor’s attorney, Paul Peterson, told ABC News. “Be that as it may, Dr. Schulenberg stands behind the care that [Prince] received. We intend to defend this case.”

The suit also names North Memorial Health, UnityPoint Health, Walgreens Co. as co-defendants. Walgreens operated the pharmacies that filled the aforementioned prescriptions; however, the company points out that its employees did not distribute the narcotics that reportedly killed the singer.

“The cause of death was determined to be fentanyl toxicity,” Walgreens Co. said in a statement to ABC News. “The investigation was closed when authorities could not identify the party responsible for providing Prince Nelson the drugs that contributed to his death. Walgreen Co. never dispensed fentanyl to Prince Nelson.”

Prince’s family is seeking damages in excess of $50,000.

The plaintiffs' attorney, John Goetz, said his clients plan to dismiss their previous lawsuit filed against the Illinois hospital that treated Prince shortly before his death.

“Prince lived in Minnesota all his life and passed away here,” Goetz explained. “So we always thought his family's lawsuit belonged in Minnesota.”