The West Australian government has offered a $1 million reward to help solve the 40-year-old mystery disappearance and suspected murder of Lisa Marie Mott.
The 12-year-old was last seen on October 30, 1980, when she left basketball courts at Collie, south of Perth.
Police Minister Michelle Roberts said it was hoped the cash on offer would generate new information in the cold case.
"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," she said.
"Arrests can still be made, even after many years, and convictions secured.
"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."
The reward was approved by state cabinet after consultation with police.
Australian Associated Press