Video (01:26) : A Minnesota doctor saw Prince twice in the month before his death - including the day before he died - and prescribed him medication, according to a search warrant. Authorities returned to Prince's estate outside Minneapolis on Tuesday. 
 
 The identity of a Twin Cities doctor who had been treating Prince several weeks before he died was revealed in a search warrant filed in Hennepin County District Court. 
 
 According to the warrant, Dr. Michael Todd Schulenberg, a family practitioner, had seen Prince twice before he was found in a Paisley Park elevator April 21. One visit occurred at the Chanhassen complex the day before Prince was found dead. 
 
 The warrant authorized the search and seizure of Prince’s medical records at North Memorial Medical Center in Robbinsdale. 
 
 Late Tuesday afternoon, local and federal investigators returned to Paisley Park, where they continued their work for more than five hours. 
 
 Schulenberg, 46, worked at North Memorial’s Minnetonka clinic, said health system spokeswoman Lesa Bader. However, the doctor no longer works with the health system. Bader declined to provide employment dates or disclose why Schulenberg no longer works there. 
 
 Carver County detective Chris Nelson said in a sworn statement used to obtain the warrant that Schulenberg had given a statement to deputies. Nelson wrote in the affidavit that Schulenberg told him that he had treated Prince on April 7 and on April 20. The doctor said he had arrived at Paisley Park the morning Prince was found in the elevator to deliver test results. The warrant does not describe the nature of the tests. It said that Schulenberg also told detectives that he had given Prince a prescription that was to be filled at a Walgreens. 
 
 A law enforcement officer walked out of a door at Paisley Park on Tuesday. About a half-dozen unmarked cars were parked there as investigators returned to the complex. 
 
 The musician was to have performed a pair of concerts in Atlanta on April 7, but postponed those shows, blaming the flu. 
 
 A source with knowledge of the investigation told the Star Tribune on Friday that the doctor had been treating Prince for withdrawal symptoms from opioid addiction several weeks before his death. The source said the doctor did not prescribe opioids to the megastar. 
 
 The warrant, filed May 6, accidentally was left unsealed until Tuesday, when Carver County learned of the mistake and sent a copy of the order sealing it to the Hennepin County court administrator. The Star Tribune obtained a copy. 
 
 Schulenberg could not be reached for comment Tuesday. A review of his medical license shows no disciplinary action against the physician, who was trained at Oregon Health & Science University and who has board certification in family medicine. 
 
 His attorney, Amy Conners, declined to comment Tuesday, citing the requirement that patient information be kept confidential. 
 
 Prince reportedly was seeking treatment for addiction to painkillers in the weeks before his death. 
 
 Representatives for the pop star reached out on April 20 to a California physician, Dr. Howard Kornfeld, who dispatched his son to meet with Prince the next day, along with another doctor who was federally certified to prescribe a medication, buprenorphine, which is used in the treatment of opioid addiction. 
 
 Schulenberg is not on the list maintained by the U.S. Food and Drug Administration of practitioners who can prescribe buprenorphine. The second Minnesota physician, who has not been publicly identified, had cleared his morning calendar to evaluate Prince on the day his body was found, the source said. The appointment never took place. 
 
 The warrant also reveals that Kirk Anthony Johnson — a close associate of Prince’s who manages Paisley Park — was present when detectives arrived at the death scene. The Star Tribune has reported that two staffers were present, along with Kornfeld’s son, Andrew, when Prince’s body was found. 
 
 The affidavit says that detective Christina Wagner interviewed Johnson, who said that Prince had been treated in the Ridgeview health system for an undescribed illness in 2014 or 2015. 
 
 Johnson could not be reached for comment. His attorney, F. Clayton Tyler, declined to comment Tuesday. 
 
 Prescription data 
 
 Meanwhile, investigators are looking into the means by which Prince received prescription opioids, which are narcotics subject to additional federal regulation. 
 
 Prescriptions of opioids are reported to the Minnesota Board of Pharmacy as part of the state’s monitoring of addicts who are obtaining the drugs from multiple practitioners. While these records can be obtained by law enforcement authorities under a search warrant, the board’s executive director, Cody Wiberg, said Tuesday that his office has no such warrants in its possession. 
 
 However, medical examiners can review the prescribing data without warrants on patients whose deaths they are investigating. So it is possible that the state opioid prescribing data has been consulted. 
 
 The Midwest Medical Examiner’s Office in Anoka is conducting the investigation to determine how Prince died. Results are pending. The Carver County Sheriff’s Office has said that neither foul play nor suicide are suspected. 
 
 Authorities arrived Tuesday afternoon at Paisley Park Studios in Chanhassen. 
 
 Shortly before 6 p.m., about a half-dozen unmarked cars were parked at Paisley Park. Private security officers also walked the perimeter and were stationed at the gates. Over the next several hours, the security crew waved cars into and out of the grounds through a main gate. 
 
 As the officers worked, dozens of people stood outside Paisley Park’s security fence to take photos of the flowers, balloons and purple memorabilia left in Prince’s honor. 
 
 Staff writers Pam Louwagie and Emma Nelson contributed to this report. ||||| A Carver County sheriff’s vehicle enters through the gates of Prince's Paisley Park home and studio in Chanhassen, Minn., Tuesday, May 10, 2016. A Minnesota doctor saw Prince twice in the month before... (Associated Press) 
 
 A Carver County sheriff’s vehicle enters through the gates of Prince's Paisley Park home and studio in Chanhassen, Minn., Tuesday, May 10, 2016. A Minnesota doctor saw Prince twice in the month before his death, including the day before he died, and prescribed him medication, according to contents of... (Associated Press) 
 
 CHANHASSEN, Minn. (AP) — A Minnesota doctor saw Prince twice in the month before his death — including the day before he died — and prescribed him medication, according to contents of a search warrant that were revealed as authorities returned to the musician's suburban Minneapolis estate as part of their investigation into what killed him. 
 
 Dr. Michael Todd Schulenberg treated Prince on April 7 and April 20, and he prescribed medications for the musician, according to the warrant, which was obtained Tuesday by at least two news outlets before authorities moved to ensure it was sealed. 
 
 Investigators interviewed Schulenberg and searched a suburban Minneapolis hospital where he worked. The warrant did not specify what medications were prescribed or whether Prince took them. 
 
 Schulenberg's attorney, Amy Conners, declined to comment late Tuesday, citing patient confidentiality. 
 
 A law enforcement official has told The Associated Press that investigators are looking into whether Prince died from an overdose and whether a doctor was prescribing him drugs in the weeks before his death. The law enforcement official has been briefed on the investigation and spoke to the AP on condition of anonymity because he was not authorized to speak to the media. 
 
 Schulenberg is the second doctor whose name has surfaced in the investigation. Last week, a lawyer for California addiction specialist Dr. Howard Kornfeld told reporters that Prince's representatives had contacted Kornfeld seeking help a day before the superstar was found dead on April 21. 
 
 On Tuesday, a sheriff's car and about a dozen unmarked vehicles entered the gates of Paisley Park. Asked what investigators were doing, Carver County Sheriff's Chief Deputy Jason Kamerud told the AP that they were "being thorough." 
 
 Kamerud declined to answer questions about the warrant that names Schulenberg, saying it was supposed to be sealed. Kamerud also said that after the contents were made public, he contacted a court administrator to ensure the warrant was sealed. 
 
 The warrant was carried out last Thursday at North Memorial Medical Center in the Minneapolis suburb of Robbinsdale. 
 
 Lesa Bader, a spokeswoman for North Memorial Medical Center, said Schulenberg was a primary care physician at its Minnetonka clinic but that he no longer works for the health care system. She declined to say why. No one answered the door at the doctor's home on Tuesday and phone messages left for him weren't returned. 
 
 Schulenberg's April 7 treatment of Prince came the day he canceled shows in Atlanta citing illness. Prince played makeup shows April 14. During his return home on April 15, his plane made an emergency stop in Moline, Illinois. The law enforcement official who spoke to the AP on condition of anonymity said Prince was found unconscious on the plane and that first responders gave him a shot of Narcan, which is used in suspected opioid overdoses. 
 
 Schulenberg told a detective that he was dropping off some results of tests that had been performed on Prince when he came upon the death scene, according to the warrant. Schulenberg also told the detective that he had prescribed Prince "medications" with the prescription to be filled at a Walgreen's. 
 
 The warrant sought "any and all medical records, documents, reports, charts, photographs, prescriptions, doctor notes and medical images for Prince Rogers Nelson." 
 
 The warrant also notes an interview with Kirk Anthony Johnson, a Paisley Park staff member and sometime drummer for Prince, who told another detective that Prince had visited the Highway 212 Medical Center not far from Paisley Park for "an illness" in 2014 or 2015. Johnson told the detective that Prince had been given fluids during the visit. 
 
 Carver County previously released a log of 911 calls to Paisley Park that showed a 53-year-old man, apparently dehydrated, taken to Highway 212 Medical Center in 2013. That man's age was given as 53; Prince would have been 55 at the time. A hospital spokeswoman said earlier she couldn't provide any information on patients due to privacy laws. 
 
 The people who found Prince dead included Kornfeld's son, Andrew Kornfeld, who had taken a redeye flight the night of April 20 but did not meet with Prince before his death. 
 
 The Kornfelds' attorney, William Mauzy, said last week that Dr. Kornfeld sent his son because he could not immediately fly to Minnesota. Mauzy said Dr. Kornfeld arranged for Prince to be evaluated by a Minnesota physician on April 21. The attorney refused to identify the Minnesota doctor, and it's not clear whether the physician was Schulenberg. 
 
 According to the Minnesota Board of Medical Practice website, Schulenberg has not been subjected to any disciplinary or corrective action in Minnesota or other states. He's a 1995 graduate of the Oregon Health Sciences University School of Medicine. His license status is listed as active. It expires Oct. 31 of this year. 
 
 The site lists no self-reported criminal convictions. State law requires the board to post felonies and gross misdemeanors that happened after July 1, 2013, in any state. 
 
 ___ 
 
 Associated Press writers Kevin Burbach, Jeff Baenen and Doug Glass contributed to this report from Minneapolis. Karnowski reported from Minneapolis.
– Prince was seeking medical treatment right up until the day before his death, according to court records. A court document filed in connection with a search warrant for the star's medical records reveals that Prince saw local physician Dr. Michael Schulenberg on April 7 and on April 20, the New York Times reports. The day after the latter appointment, the doctor, who had prescribed medication for Prince and ordered tests, turned up at the star's Paisley Park compound to discover that his patient was already dead. Court documents state that Schulenberg gave Prince a prescription that was to be filled at a Walgreens, though it's not clear whether the singer ever did so, reports the Los Angeles Times. Schulenberg, 46, was employed at North Memorial Medical Center in a Minneapolis suburb at the time of Prince's death, but the health system now says he no longer works there, the Star Tribune reports. Prince's cause of death has yet to be established, but investigators suspect a prescription drug overdose is to blame, and they want to speak to an addiction specialist who sent his son to Prince's house on an overnight flight the day before he died. The search warrant for North Memorial sought "all medical records, documents, reports, charts, photographs, prescriptions, doctor notes, and medical images for Prince Rogers Nelson," the AP notes. (Gene Simmons calls Prince's death "pathetic.")