The body of the victim, Odin Lloyd, 27, who played football for the Boston Bandits, was discovered after a night out with Hernandez and two other men, the source told the station.
The four men left in a car together, driven at one point by Hernandez, but only three men returned to Hernandez's home at the end of the night and Lloyd was not one of them, the source told the station.
Police have not named any suspects and Hernandez and his lawyers have not addressed the media.
Police have also issued a "BOLO" or "be on the lookout" for a silver Chrysler 300 rental car with Rhode Island registration which may have a connection to the homicide. A 2013 Chevrolet Suburban rented in Hernandez's name emerged as a key piece of evidence in the investigation.