MINNEAPOLIS >> Prince thought he was taking a common painkiller but instead ingested a counterfeit pill that he probably did not know contained fentanyl, a Minnesota prosecutor said today as he announced that no charges would be filed in the musician’s death.

Carver County Attorney Mark Metz said Prince had suffered from pain for years and was addicted to pain medication. While some of the superstar’s associates might have enabled his drug habit and tried to protect his privacy, authorities found “no direct evidence that a specific person provided the fentanyl.”

“In all likelihood, Prince had no idea that he was taking a counterfeit pill that could kill him,” Metz said.

Metz’s announcement came just hours after the U.S. Attorney’s Office announced that a doctor who was accused of illegally prescribing an opioid for Prince agreed to pay $30,000 to settle a civil violation of a federal drug law. Dr. Michael Todd Schulenberg allegedly wrote a prescription for oxycodone in the name of Prince’s bodyguard, intending for the potent painkiller to go Prince. That prescription was not linked to Prince’s death.

Prince was 57 when he was found alone and unresponsive in an elevator at his Paisley Park studio compound on April 21, 2016. His death sparked a national outpouring of grief and prompted a joint investigation by Carver County and federal authorities.

An autopsy found he died of an accidental overdose of fentanyl, a synthetic opioid 50 times more powerful than heroin.

Metz said several pills were found at the Paisley Park complex after Prince died, and many of them were not in their original pharmaceutical containers. Some of those pills were later determined to be counterfeit, and state and federal authorities have been investigating the source of the fentanyl for nearly two years.

“My focus was lasered in on trying to find out who provided that fentanyl, and we just don’t know where he got it,” Metz said. “We may never know. … It’s pretty clear from the evidence that he did not know, and the people around him didn’t know, that he was taking fentanyl.”

Metz’s announcement effectively closed the case.

“There is no doubt that the actions of individuals will be criticized, questioned, and judged in the days and weeks to come,” Metz said. “But suspicions and innuendo are categorically insufficient to support any criminal charges.”

After the announcement, the U.S. Attorney’s Office said it also had no credible evidence that would lead to federal criminal charges. A law enforcement official close to the investigation told the Associated Press that the federal investigation is now inactive unless new information emerges. The official spoke on condition of anonymity because the federal case remains open.

But authorities alleged Schulenberg, a family physician who saw Prince twice before he died, illegally prescribed an opioid to Prince in violation of the Controlled Substances Act. Prosecutors say Schulenberg wrote a prescription for oxycodone to Kirk Johnson, Prince’s close friend and bodyguard, on April 14, 2016, with the intent that it go to Prince.

Schulenberg’s attorney, Amy Conners, has disputed that and did so again Thursday, saying that Schulenberg settled the case to avoid the expense and uncertain outcome of litigation. The doctor admitted no facts or liability in the settlement, which includes stricter monitoring of his prescribing practices. Schulenberg is not the target of a criminal investigation.

Oxycodone, the generic name for the active ingredient in OxyContin, was not listed as a cause of Prince’s death. But it is part of a family of painkillers driving the nation’s addiction and overdose epidemic, according to the Centers for Disease Control and Prevention. Nearly 2 million Americans abused or were addicted to prescription opioids, including oxycodone, in 2014.

“Doctors are trusted medical professionals and, in the midst of our opioid crisis, they must be part of the solution,” U.S. Attorney Greg Brooker said Thursday.

A confidential toxicology report obtained by the AP in March showed high concentrations of fentanyl in the singer’s blood, liver and stomach. The concentration of fentanyl in Prince’s blood alone was 67.8 micrograms per liter, which outside experts called “exceedingly high.”

Prince did not have a prescription for fentanyl.

While many who knew Prince over the years said he had a reputation for clean living, some said he also struggled with pain after years of intense performing. Documents unsealed in the case paint a picture of a man struggling with an addiction to prescription opioids and withdrawal symptoms. The papers also show there were efforts to get him help.

Schulenberg saw Prince on April 7, 2016, at Johnson’s request, according to authorities, and prescribed Vitamin D and a nausea medication — under Johnson’s name. Johnson then called Schulenberg on April 14, asking the doctor to prescribe a pain medication for Prince’s hip. Schulenberg did so, Metz said.

Johnson’s attorney, F. Clayton Tyler, said Thursday’s decision on criminal charges affirms Johnson’s innocence. He said Johnson “continues to deny that he had anything to do with the death of his close friend.”

On the night of April 14 to April 15, Prince passed out on a flight from Atlanta, and the private plane made an emergency stop in Moline, Illinois. The musician had to be revived with two doses of a drug that reverses the effects of an opioid overdose.

The day before his death, Paisley Park staffers contacted California addiction specialist Dr. Howard Kornfeld. The doctor sent his son, Andrew, to Minnesota that night, and the younger Kornfeld was among those who found Prince’s body. Andrew Kornfeld was carrying buprenorphine, a medication that can be used to help treat opioid addiction.