The father of a missing Melbourne schoolgirl believes she's still alive nearly three years after her disappearance as police launch a $1 million reward to catch her abductor.
Siriyakorn "Bung" Siriboon was last seen on June 2, 2011 by a neighbour three doors down from her house in Boronia, in the city's outer east, as she walked to school in her uniform.
While police have numerous people of interest in the case, a taskforce has been unable to determine what happened to the 13-year-old beyond a theory of abduction.
Bung's stepfather Fred Pattison says he hopes the police reward announced on Tuesday will help solve the case.
"We still believe she's alive," he told reporters.
"I believe that. We want to believe that. We can't believe anything else."
He said life had been on hold for his family as he pleaded with whoever may know something to finally come forward.
"Think if it was your family or your daughter," he said.
"It's time for somebody to say something."
Homicide Squad Detective Inspector John Potter says it is a baffling and frustrating case, but he remains hopeful the reward will entice tips to flow in.
"It's a life-changing amount of money," he said.
A 24-year-old man was twice arrested last year - in August and in October - and questioned over the disappearance, but was released without charge.
Police say there have been no arrests since then and several registered sex offenders also remain on the police radar.
Det Insp Potter said the reward was aimed at an accomplice or someone who was told what happened and kept it a secret.
Anyone who does come forward and reveals who is behind the disappearance won't be prosecuted, even if they were involved, he said.

