Maribyrnong Crime Investigation Unit Detectives are investigating following a burglary in Braybrook on Wednesday 26 April, Victoria Police say.
It is believed two offenders attended a disused factory in Scotland Street between 4 and 4.30am.
Once inside the building the offenders have used a white Toyota LandCruiser with a distinctive tray body to drag a 10 tonne electrical transformer onto the driveway.
The transformer was damaged when it was being moved causing it to spill hundreds of litres of toxic oil onto the roadway which had to be cleaned up by the EPA.
After leaving the scene the offenders returned a short time later with a distinctive tandem trailer but left empty handed.
Investigators have released CCTV images of two men they believe may be able to assist with their enquiries.
Anyone with information is urged to contact Crime Stoppers.