Frontman James Hetfield and his bandmates offered up a reward for details leading to the whereabouts of Virginia Tech college student Morgan Harrington after she went missing after attending one of their concerts.
The 20 year old's remains were found three months later in a field 10 miles from the concert venue.
Three years after the gruesome discovery, police are still looking for the suspect, and now Metallica have joined another search - this time to bring Harrington's killer to justice.
In a video posted online, Hetfield urges anyone with information to come forward with tips.
He says, "Any information, no matter how small you might think it is, could be that crucial piece investigators need to help solve the case." (KL/RS/MJ)