The 16-year-old disappeared while she was working as a lifeguard in Warren. Her remains were found three years later.
Investigators have returned to the site where some of the remains of Molly Bish were found in 2003.
The family of Molly Bish has made an appeal to state investigators to allow the FBI to help hunt for her killer.
Photographs of Pouliot were startling to the family of Molly Bish, the Warren lifeguard who disappeared seven years after Piirainen was killed.