A new search for the remains of West Australian teenager Hayley Dodd has been sparked by comments made at trial by her convicted killer Francis John Wark.
Special crime detectives and forensic officers are continuing to scour Wark's former property in rural Badgingarra, near where Hayley was last seen in 1999.
Wark, 65, was acquitted by a WA Supreme Court jury of murdering Hayley after a six-week retrial but found guilty of the lesser charge of manslaughter.
Justice Stephen Hall last week jailed Wark for 18 years - six years longer than the previous record manslaughter sentence in WA.
Police on Wednesday demolished a large water tank on the Badgingarra property so they could drill to a depth of two metres underneath.
The sprawling property was extensively searched after Hayley's disappearance but officers did not look under the tank at that time.
Police Commissioner Chris Dawson said the fresh search was prompted by evidence given by Wark during his retrial.
"During the recent trial, in which Wark was convicted, he was examined and he made some comments while he was in the dock," Mr Dawson told Perth radio 6PR.
"He was responding to questions about what might be under certain areas, including the water tank.
"It is painstaking but ... we are not going to give up looking for Hayley."
Hayley was 17 when she was last seen alive in July 1999, walking along a road near Badgingarra, about 200 kilometres north of Perth.
Her body has never been found.
Wark will be eligible for parole after 16 years but is subject to the state's "no body, no parole" law.
Detectives intend to re-interview Wark in relation to the latest search, Detective Superintendent Quentin Flatman told reporters.
"We'll be asking him further questions about this," he said.
Mr Dawson said there appeared to be "at least several more opportunities" which police wanted to conclusively eliminate.
"The place looked like a mining site last time I was there. Over the years there (have) been additions and alterations," he said.
"Hayley's family deserves a resolution. Our thoughts remain with the family and we are going to keep looking."
In his sentencing remarks, Justice Hall found Wark had lured Hayley into his ute with an intention to sexually assault her and had attacked her when she resisted.
He then disposed of her body with "callous disregard" in a way that ensured he would not be linked to her death.
Wark was only charged in 2015 after a cold case review linked an earring and a strand of hair found in the ute to Hayley.
Hayley's mother Margaret Dodd welcomed the sentence after earlier appealing directly to Wark to reveal where Hayley's body was left.
Wark has been behind bars since 2007, when he was jailed for raping a woman he picked up in a remote part of Queensland.
Justice Hall said Wark's offending fell into the worst category for manslaughter given the apparent sexual motivation and Hayley's youth and vulnerability.
Australian Associated Press