Prosecutors alleged Dr. Michael Todd Schulenberg wrote a prescription for oxycodone in the name of Prince's bodyguard, intending it to go Prince.
Carver County attorney Mark Metz said in a statement: "Despite the intensive law enforcement investigation, there is no reliable evidence showing how Prince obtained the counterfeit Vicodin laced with fentanyl, or who else may have had a role in delivering the counterfeit Vicodin to Prince".
Dr Schulenberg admitted no liability as part of the settlement and has maintained he did not prescribe drugs to anyone with the intention they be redirected to Prince. Schulenberg did so, again under Johnson's name, Metz said.
"Purple Rain" singer Prince died at age 57 in April 2016 at his Minnesota residence.
Sen. Amy Klobuchar took a moment to remember Prince on the Senate floor.
After the second shot woke up Prince and paramedics asked how he was doing, Johnson interjected and said "Prince feels fine".
Metz said some of Prince's friends might have enabled him as they tried to protect him.
The documents show that Johnson contacted Schulenberg again on April 18, and expressed concern that Prince was struggling with opioids.
"There is no evidence the pills that killed Prince were prescribed by a doctor".
"There is no doubt that the actions of individuals around Prince will be criticised, questioned and judged in the days and weeks to come".
Federal authorities say they will not file criminal charges either. An autopsy found he died of an accidental overdose of fentanyl. The official spoke on condition of anonymity because the federal case remains open.
Prince was treated with an IV that day, while officials say Schulenberg also prescribed nausea medication and Vitamin D under Johnson's name. The medical report claimed that there was 67.8 micrograms of fentanyl per liter of blood in his bloodstream.