Merri-bek Crime Investigation Unit detectives have released CCTV after a suspicious unit fire Glenroy at the end of last year.
Police and emergency services were called to the Daly Street blaze just before 7am on Thursday, 20 November.
There were two occupants inside the premises at the time, but no one was injured.
CCTV shows a man fleeing the scene on a motorbike shortly before the blaze took hold.
He is perceived to be Caucasian with a solid build and was wearing a black jumper, grey shorts, black shoes and a white motorbike helmet.
The motorbike is believed to be a dark coloured Honda NSC110 Dio.
Anyone who witnessed the incident, with footage or anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit an online confidential report at www.crimestoppersvic.com.au.
