Thieves stole two-and-a-half tonnes of copper wiring after breaking into a recycling business in Wellingborough.
The theft happened on Monday, March 7, some time between 2.30am and 4.35am, when the offenders broke into WJ Redden and Sons in Leys Road.
CCTV footage shows that at about 4.20am, a vehicle – possibly an estate – arrived at the premises and the offenders loaded part of the wiring into it.
At 4.30am, a second car – possibly a silver Citroen Picasso – arrived and two men got into it before it was driven away.
Officers have released CCTV images two other men seen walking down Leys Road.
One of them was wearing a jacket with a fur hood.
The second was bald with a goatee beard and was wearing a T-shirt and jeans.
Witnesses to the incident, or anyone with information, are asked to call police on 101 or Crimestoppers anonymously on 0800 555111.