Police have confirmed to 1 NEWS that the Ashburton Work and Income double murderer Russell John Tully is a "person of interest" in the 20 year old Kirsty Bentley investigation.
Fifteen-year-old Kirsty Bentley disappeared while walking her dog on New Year's Eve in 1998.
Two weeks later her body was found in scrub in the Rakaia Gorge, 40 kilometres from her family home in Ashburton.
Detective Inspector Greg Murton says there were "literally hundreds" of persons of interests during the initial investigation into Bentley's death and "they're either eliminated from the list or they stay there".
He said police wouldn't confirm at what stage 51-year-old Tully appeared on the list.
Tully is currently serving life imprisonment for the 2014 murders of WINZ receptionist Peggy Turuhira Noble and case worker Susan Leigh Cleveland.
Tully's lawyer, Craig Tuck, said his client was "horrified that his name is linked to Ms Bentley's murder, based on no evidence at all".