Known only as “John” in a Providence police affidavit, the source is being hailed by investigators as the key figure who gave law enforcement the details needed to determine who was behind the Brown shooting and the killing of an MIT professor.

The Brown University attack was found deceased Thursday, capping six days of wall-to-wall coverage of a law enforcement manhunt.

"Tonight our Providence neighbors can finally breathe a little easier," Providence Mayor Brett Smiley told reporters.

The shooter’s body was found at a storage unit in New Hampshire along with two firearms.