PHOTOS: Investigation gives first look into Prince's vault

CHANHASSEN, Minn. (KMSP) - A heavy metal door at Paisley Park has for decades guarded a substantial trove of recordings and other valuable artifacts from the career of Prince Rogers Nelson, a metaphor as good as any for the musician's private nature and equally bright future as an artist. 

The world is now getting its first look inside the musician's vault following the conclusion of a criminal investigation into Prince's death, nearly two years to the day since his overdose inside the compound where he lived and worked.

Hundreds of pictures of the room were released Thursday after Carver County Attorney Mike Metz announced he was not filing any criminal charges in the case, part of a much larger case file compiled by authorities as they investigated the musician's April 2016 death.

Public data released six weeks after his death showed he died of an accidental overdose of fentanyl, a synthetic opioid 50 times more powerful than heroin. According to Metz, evidence from the investigation shows Prince thought he was taking Vicodin, but the pills he took were counterfeit and contained fentanyl. The pills were an exact imitation of real Vicodin pills. 

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