A special police taskforce has been set up to try to solve the four-month-old disappearance of Melbourne schoolgirl Siriyakorn "Bung" Siriboon.
Police believe the 13-year-old was abducted on her way to school in Boronia, in Melbourne's east, on June 2 but admit they have no suspects.
A dedicated unit, Taskforce Puma, has been set up which will be led by homicide squad Detective Senior Sergeant David Snare.
Crime department Detective Superintendent Brett Guerin said the investigation had been reviewed and police believed the formation of the taskforce was the next step.
"It will be 21 weeks this Thursday since Bung was last seen by her parents leaving home for school," Det Supt Guerin said in a statement on Tuesday.
"Investigators continue to pursue a number of lines of inquiry and have received many calls but we currently have no suspects.
"Somebody must know something; it is impossible for a 13-year-old to vanish off the face of the earth."
Bung was last seen leaving home in her blue-and-white school uniform about 8.30am on Thursday June 2.
Police have received more than 500 calls from the public since the investigation began.
Investigators have been cross referencing the files of known sex offenders and continue to conduct doorknocks throughout the area, police said.
