On the 40th anniversary of Collie girl Lisa Mott's disappearance, the WA government have raised the reward for information to $1 million.
It is hoped the reward might help generate new information and help Police solve the 40-year cold case mystery.
Lisa was 12 years-old in 1980 when she was last seen on Forrest Street, Collie at 8.30pm.
She had just left the basketball courts and was expecting to be collected by a family friend and taken home.
Despite extensive enquiries and intense media coverage, the person or persons responsible for Lisa's disappearance and suspected homicide have not been identified.
Police minister Michelle Roberts said the police's work with the Claremont case shows that cold cases could be solved.
"Arrests can still be made, even after many years, and convictions secured," she said.
"Neither the police, nor the Government gives up on any of these cases and we want to encourage the community not to give up either.
"That is why the Government has increased this reward for information, regarding the disappearance and suspected homicide of Lisa Mott.
"We hope that the announcement of a $1 million reward will encourage someone to come forward with information that can end four decades of heartache for her family."
The Government may be prepared to consider recommending a protection from prosecution, or pardon for any informant with information that leads to the conviction of the person or persons responsible for the disappearance and suspected homicide provided that the informant was not directly responsible for the disappearance and suspected homicide.
Other WA cold cases: