A central figure in the Prince death investigation is the superstar’s longtime friend and right-hand man, who had a cameo in the movie “Purple Rain.”

According to a search warrant, detectives interviewed Kirk A. Johnson — a former Prince drummer and current manager of the singer’s Paisley Park estate — following the performer’s unexpected death last month.

The court document, obtained by the Los Angeles Times, discloses that police seized Prince Rogers Nelson’s medical records from a Minneapolis-area hospital in early May. Investigators were particularly interested in files involving a family-medicine doctor who had treated Prince in the weeks before the singer was found dead April 21 in a Paisley Park elevator.

The warrant also reveals Johnson, 51, told detectives that Prince had gone to another local medical clinic for an illness in 2014 or 2015.

Former Prince drummer and Paisley Park manager Kirk Johnson. (Facebook)More

Despite weeks of media speculation that an addiction to prescription painkillers may have led to Prince’s sudden death, authorities haven’t announced how the 57-year-old artist died.

“I am unable to provide any comment or clarification about specifics of the investigation,” Carver County Sheriff’s Office Chief Deputy Jason Kamerud told Yahoo News on Tuesday.

The singer’s inner circle has also kept mum.

Johnson, who oversaw Prince’s sprawling studios and home in Chanhassen, Minn., and was described by the Minneapolis Star Tribune as Prince’s de facto bodyguard, has hired Minneapolis criminal defense attorney F. Clayton Tyler.

Johnson hasn’t spoken publicly about Prince’s death, and Yahoo News messages to him weren’t returned. Johnson is also a personal trainer at Life Time Fitness in Chanhassen but hasn’t been to the gym since Prince’s passing, the AP reports.

He did, however, send a text message to the Star Tribune on Friday.

“Right now, it’s just too painful to even speak,” Johnson told the newspaper.

Johnson graduated from Minneapolis Central High School in 1982, six years after Prince. In the 1984 rock musical drama “Purple Rain,” Johnson makes a brief appearance as a dancer on the balcony at the nightclub First Avenue, where Prince filmed his iconic movie.

Johnson, a drummer for other bands through the years, is credited for various roles on 11 Prince albums in the 1990s. He was the singer’s best man when Prince married backup singer Mayte Garcia on Valentine’s Day 1996.

Tax returns show Johnson, known by some as Kirky J, served as president of Prince’s Love 4 One Another Charities for a number of years before becoming estate manager at Paisley Park in 2011. Public records indicate Johnson has lived in a Prince-owned home two miles from Paisley Park for several years.

“I’m pretty sure Kirky J knows more about our beloved Prince than any other living soul,” a commenter wrote earlier this month on Prince.org, a fan community forum.

The Carver County Sheriff’s Office declined to answer questions about Johnson’s role in the investigation.

The Star Tribune, citing unidentified sources, reports investigators are trying to determine whether opioid painkillers such as oxycodone or hydrocodone played a role in Prince’s death and if they were supplied to him illegally. Last fall, the newspaper’s review of state death records revealed opioid overuse now kills more Minnesotans each year than homicide.

A month before the singer’s death, Johnson’s lawyer, Tyler, warned on his website that Minnesota authorities are cracking down prescription drug abuse.

“Sharing your medication with a friend who is struggling with pain might be well-meaning, but under Minnesota’s broad definition of ‘sell,’ you could be charged with felony drug sales,” Tyler wrote in a blog post.

Tyler did not return messages seeking comment for this story.

The week before Prince’s death, a private jet carrying the musician home from a concert in Atlanta had to make an emergency landing in Moline, Ill., when the singer lost consciousness.

“[Patient] was carried down from an airplane by [patient’s] body guard,” a paramedic wrote in a report about the April 15 incident. Emergency workers who met the jet gave Prince a shot of the opioid antidote Narcan, the Star Tribune reported.

According to Federal Aviation Administration records, Chanhassen-based Life Time Fitness — the health club where Johnson works as a trainer and group fitness instructor — owns the plane involved in the emergency landing. The gym’s spokeswoman declined to answer questions about the company’s plane and Prince.

Johnson traded text messages with a Star Tribune reporter several hours after the emergency landing.

“All is good. Home and well,” Johnson wrote.

“What happened?” the reporter asked.

“Bad dehydration. Sorry, I can’t talk right now. Hey u and 2 million others are on me, but I’m not the publicist. Sorry.”

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