Authorities investigating Prince's death are focusing on the role that painkillers apparently played in both his fatal collapse at Paisley Park and in the medical emergency that forced his private plane to land in the middle of the night in Moline, Ill., days before.

Several sources familiar with the probe have told the Star Tribune that painkillers may have taken a toll on the musician during his final weeks.

Five days before he was found dead at his Chanhassen home and studio, Prince's plane — en route to Minneapolis from Atlanta, where he had played two concerts in one night — made an emergency landing in Moline because he was overdosing from an opioid, the sources said. Once the plane landed, Prince was given a shot of the opioid antidote Narcan by emergency personnel; he was taken to a hospital, but left within a few hours.

Meanwhile, a longtime attorney for two of Prince's siblings has told the Star Tribune — and local authorities — that his clients informed him more than a decade ago Prince had "substantial" drug problems with the opioid painkiller Percocet and cocaine.

The attorney, Michael Padden, said that Lorna Nelson and Duane Nelson often discussed with him Prince's drug problems, adding that "both were really concerned it would end his life prematurely." Padden said Duane Nelson told him that he paid straw buyers to obtain prescriptions that he then gave to Prince.

Lorna Nelson died in 2006, and Duane Nelson five years later.

"Lorna told me that her brother would die young … before his time and of a heart attack," Padden said in a videotaped interview with the Star Tribune.

While Prince may have been in pain related to years of physically demanding live concerts, former band member and close friend Sheila E. said Sunday that she has "never seen him take anything, not even aspirin, in the 38 years I've known him."

Twin Cities limo driver Robbie Paster, Prince's valet and personal assistant from 1984 to 1992, said Monday, "I never knew of any opiate or cocaine problem. There's no way you can do both of those and be as driven as he was. I never saw it."

Prince's longtime lawyer, L. Londell McMillan, told the Associated Press Monday night that he spoke to Prince the Sunday before he died. "He said he was doing perfect," McMillan said.

Asked by AP about reports of a possible drug overdose on Prince's recent flight back from Atlanta, McMillan said that while Prince may have been in pain and may have taken medication from time to time, he was "not on any drugs that would be any cause for concern."

The Carver County Sheriff's Office said last week that a final cause of death likely won't be made public for weeks. They said Monday that they want to wait for reports from the medical examiner and toxicology results.

"We are quite a ways out," Carver County Sheriff's Office Chief Deputy Jason Kamerud said.

Prince was found unresponsive Thursday morning in an elevator at Paisley Park. Three people were present when police arrived, but they have not been identified.

Carver County Sheriff Jim Olson said last week that investigators don't suspect foul play or suicide in Prince's death.

Sister grieving

Maurice Phillips, the husband of Prince's sister, Tyka Nelson, said Monday the family didn't want to comment on the investigation. He said his wife is devastated.

"We just want to stay out of it and let the police handle it," he said. "She's still in the grieving process."

Told about Padden's comments about Prince's use of painkillers, Phillips said he doesn't know if they're true.

He was upset with media stories that reported him saying Prince hadn't slept in days before his death; Phillips said he had been misquoted.

Phillips asked media companies to give the family room to grieve. "Just give us our privacy," he said.

Meanwhile, fire officials in Moline, the department that responded when Prince's plane landed in the middle of the night, declined to comment on that night's events.

According to a 7-minute air traffic control recording before the emergency landing in Moline, controllers initially were confused about the nature of the emergency beyond the fact that there was an "unresponsive passenger."

Nearly two minutes into the recording, air traffic control says that Crash Fire Rescue will meet the plane.

After more than a minute of silence, one air traffic controller confirms that "everything's coordinated."

Another two minutes pass before the pilot confirms that the plane is on the ground in Moline.

Policies regarding Narcan

In nearby Rock Island, Ill., fire department units are staffed with paramedics who operate under the same local health system's medical orders, Rock Island Fire Chief Jeff Yerkey said.

Ambulances in the system have been carrying Narcan for years, Yerkey said.

While Narcan's purpose is to counteract the effects of opioids, he said, firefighters may give the drug to an unresponsive person without knowing whether the person has ingested opioids.

There are "no real side effects or harm in giving it," Yerkey said, even if medical tests later determine that the person's condition wasn't the result of opioid use. Severe withdrawal symptoms can occur, but only for people who are on opioids.

Receiving a nasal or intravenous dose of naloxone (a generic name for Narcan) at the scene of an emergency isn't unusual.

Minnesota in 2014 created Steve's Law, named after an overdose victim, which permitted all first-responders to administer naloxone under a physician's authority and granted immunity to bystanders who administer the drug to someone suffering an overdose. Illinois went a step further last fall, requiring that all ambulance personnel, firefighters and police officers who respond to medical emergencies be trained in administering naloxone.

The drug usually takes effect in 2 to 3 minutes by occupying opioid receptors in the brain.

After Prince's death, Carver County officials said that Narcan was not administered to Prince at Paisley Park.

Padden, a Twin Cities attorney who represented some of the plaintiffs in the wrongful-death and injury suits claim against Toyota, said that "around 2001" he received information from Lorna and Duane Nelson that Prince used Percocet and cocaine.

Duane Nelson, Prince's stepbrother, and Prince were in the same grade at school and played on the Bryant Junior High School basketball team.

During Prince's professional career, Duane and Prince had a sometimes strained relationship, though Duane worked on Prince's security staff at times.

Padden, who filed "four or five" lawsuits against Prince and Paisley Park in the past, said he eventually developed a personal relationship with Duane and Lorna Nelson, who hired him for other cases. In one, Padden represented Duane Nelson in a suit against Prince after Duane was fired by the musician.

Padden said that the first he had heard of Percocet, he'd heard it from Duane Nelson. He said Lorna Nelson later corroborated what Duane Nelson had told him about Prince's use of the drug and cocaine.

Padden said he has spoken with investigators about allegations of Prince's drug use.

Padden said he didn't think that either Lorna or Duane Nelson had reason to mislead him. "I guess anything's possible, but all I can tell you is that his sister independently corroborated every single thing Duane said to me," he said. "It wasn't like I was proactive seeking information."

Story written by David Chanen (david.chanen@startribune.com), with contributions from Pam Louwagie, Stephen Montemayor, Jon Bream, Jeremy Olson, Emma Nelson, Matt McKinney, Karen Zamora and C.J.