An elderly man had his bank cards stolen from him by thieves after they pretended to help him.
Police are investigating a theft which happened at a cash machine in Shenley on October 13.
Police said a man in his 90s was using the ATM outside Tesco Express at around 10am when he was approached by a group of people.
It was reported to officers that they tried to help him use the machine but they actually took his bank cards.
The victim's cards were later used at Tesco Express in Radlett and Tesco Express in Leavesden - with hundreds of pounds spent.
Police have released CCTV images of three people they believe may be able to help with their enquiries into the theft.
PC Paul Francis, from the Potters Bar and Shenley safer neighbourhood team, said: "This was a horribly callous crime, targeting a vulnerable victim and we are working hard to find those responsible.
"We believe that those pictured were in the area at the time of the offence and they could have vital information that will assist our enquiries. I appreciate that the male’s face is not visible but hopefully someone might recognise the distinctive clothing.
"If you recognise the people pictured or have information about what happened, please get in touch by calling the non-emergency number 101 or emailing me at paul.francis2@herts.pnn.police.uk quoting crime reference 41/82877/20."
Anyone with information can also contact Crimestoppers anonymously by visiting crimestoppers-uk.org.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here