MINNEAPOLIS (AP) — The Latest on the investigation into the death of Prince, who was found unresponsive on April 21, 2016, after a fentanyl overdose (all times local):

9:15 a.m.

One of Prince's sisters is expressing disappointment about the way the investigation into her brother's death was handled.

Sharon L. Nelson tweeted Friday : "There is so much about Prince's death and this investigation that troubles me and millions of #prince fans around the world."

She questions why authorities didn't immediately collect Prince's computer, files and other records after he died. In another tweet , she references a KSTP-TV article about an investigator who regretted not immediately searching Prince's computer.

She says it "was disappointing and hurtful" and expresses hope that the federal government will do better.

Prince was found unresponsive on April 21, 2016, after a fentanyl overdose.

State prosecutors say they haven't determined the source of the fentanyl and no charges will be filed. A federal investigation is now inactive unless new information comes forward.

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12:30 a.m.

Investigative files released as prosecutors closed their probe into Prince's death show that his closest confidants had grown increasingly worried about his health in the days before he died — and that they tried to get him help.

But none of his inner circle was able to give investigators the insight they needed to determine where Prince got the fentanyl that killed him.

The files were made public as a county prosecutor announced that no criminal charges would be brought in the case.

Carver County Attorney Mark Metz says investigators believe that Prince didn't know he was taking counterfeit pills that contained fentanyl.

And Metz says he doesn't think the people around Prince knew it either.