Detectives from the Arson and Explosives Squad are today releasing CCTV footage and images following an explosion in Carrum Downs in August.
Investigators have been told an explosive device was ignited at a reserve on Hillview Drive about 5pm on 28 August.
The device was propelled into the sky before it crashed into the roof of a nearby home about 150 metres away.
The impact caused extensive damage to the roof as well as inside the property.
Two occupants who were home at the time, were not physically injured.
Investigators are hoping the images released today which depict two people will assist in identifying the pair who they believe will be able to assist with the investigation.
The man is described as Caucasian in appearance, approximately 180cm tall with a medium build.
He was wearing dark pants and a grey long sleeved hoodie at the time.
The woman is also described as Caucasian in appearance with a medium build and long hair tied in a ponytail.
She was wearing a dark hoodie, jeans and tanned boots at the time.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report online at www.crimestoppersvic.com.au