Detectives are urging a man to come forward after a fire gutted a Geelong West church last Friday.
The man is a potential witness to the fire and Geelong Crime Investigation Unit detectives have been told he was riding a dark coloured mountain bike near the scene before he stopped to watch the Pakington Street blaze for a short time.
He engaged in conversation with another man, who police have spoken to, before riding off just after 4.30am.
Detectives want to speak to the man and have released footage of him riding past the fire scene, captured from a mobile phone, in the hope it will assist the investigation.
The man is described as Caucasian in appearance, thirties and about 182cm tall.
He was wearing a cap underneath his bike helmet, a black and white striped shirt under a blue coloured hoodie, shorts, and fingerless gloves and was carrying a light yellow or cream coloured backpack.
Much of the 103-year-old Presbyterian church on Pakington Street had to be knocked down following the fire, which is being treated a suspicious.
Anyone with information about the fire or anyone who knows the identity of the man is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au
Police have released video taken on a mobile phone at the time of the blaze