A two-year investigation into the death of musician Prince has been closed after authorities said no criminal charges will be filed. <br /> Prosecutors in Minnesota said Thursday that law enforcement officials were unable to find evidence on how Prince obtained a counterfeit pill that killed him.<br />Carver County attorney Mark Metz also said they were unable to determine its source or find evidence of intentional wrongdoing.<br />The late singer, who apparently suffered from painkiller addiction, died from an accidental overdose of the painkiller fentanyl, an opioid about 30 to 50 times more powerful than heroin. <br />
