Auction website eBay has been enlisted to train Cambridgeshire Police officers in tackling online crime.
Officers are being taught by eBay's law enforcement team on to how to use the site and how to keep local residents safe online.
The training programme includes how to fight fraud and how to spot and avoid counterfeit goods for sale.
Police are also shown how to analyse user profiles and trading history for their investigations.
Steve Edwards from eBay said: "Trust is the engine of eBay and... we have a duty to make it as safe and secure as possible."
A Cambridgeshire police they hoped the session would provide a better understanding of online marketplaces and how to use them as part of investigations.