Victoria Police's arson and explosive squad will investigate what caused a factory fire in Melbourne's inner west, after fire experts said the fire's cause "may be suspicious".
The police takeover of the investigation comes after the fire in the asbestos-ridden West Footscray factory began early Thursday, demanding more than 140 firefighters.
Dark billowing plumes of smoke could be seen across Melbourne and 50 schools and child care centres closed because of it.
The Metropolitan Fire Brigade has confirmed the smoke was toxic.
Residents in surrounding suburbs remain warned to avoid waterways contaminated with water run-off.
The blaze, which involved multiple explosions throughout Thursday, took 17 hours to bring under control and still continues to smoulder.
MFB's specialist fire investigators announced Saturday afternoon they had referred their investigation of the fire on to police.
"This is based on evidence which indicates that the cause of the fire may be suspicious," an MFB statement said.
Victoria Police said on Saturday its own detectives had not yet been able to begin their investigation "as the scene has not been deemed safe".
"The exact cause of the fire is yet to be established," Victoria Police's statement said.
Documents obtained by AAP show the Tottenham factory is owned by Danbol Pty Ltd, whose sole director is Christopher James Baldwin, 74, of Mooroopna, near Shepparton.
Earlier this month, Mr Baldwin's accounting firm was reportedly targeted in Australian Tax Office raids.
"I just own the property and that's it," he has told the Nine Network.
