Hamilton Criminal Investigation Unit detectives are appealing for witnesses following a suspicious fire near the railway overpass in French Street on January 14, Victoria Police say.
The fire, which police believe was lit at 6.45pm, spread over 40 square meters before being extinguished.
There were no injuries or damage to property.
Investigators would like to speak to a woman whom they believe may be able to help them with their enquiries and have released images of the woman.
She is believed to be of Caucasian appearance and has a heavy build, long dark hair and aged in 20s or early 30s.
She was seen leaving the area on foot, passing a number of shops along Gray Street.
Anyone with information regarding the incident or the identity of the woman is urged to contact Crime Stoppers.