Victorian homicide police are offering a $1 million reward for information about missing Melbourne schoolgirl Siriyakorn “Bung” Siriboon.

The Boronia Heights College student left her home in Elsie Street, Boronia, in Melbourne’s east, on Thursday June 2, 2011 and was last seen walking towards Albert Avenue.

In December, homicide squad detectives said they had arrested and questioned a man, 24, who claimed to have hit and killed Bung while driving in his car on the morning she disappeared, then panicked and disposed of her body at a local reserve.

However, a search of the Old Joe’s Creek retarding basin yielded nothing.

Homicide squad detectives told the ABC they had also seized “items of interest” from the man, and that they are being forensically tested.

Detectives have investigated more than 1,200 pieces of information since Bung went missing but are still not clear about what happened to her.

The ABC revealed in October that Victoria Police was shutting down the Puma taskforce, which was set up to investigate Bung’s disappearance.

Senior police stressed that the dismantling of the squad did not mean police had scaled back the investigation or given up hope of finding whoever is responsible for Bung’s disappearance.

The million-dollar reward will be paid at the discretion of the Chief Commissioner, for information leading to the conviction of the person or persons responsible for Bung’s disappearance.