They were called by people claiming to be from the police who warned they needed to move money from their accounts because of suspicious activity.
The scammers then arranged to send someone to pick up the money for safekeeping – but they actually pocketed it.
Nottinghamshire Police detectives have issued a CCTV image of a man they wish to speak to in connection with reports the courier frauds.
Both victims from Retford reported the fraud to officers in October following a number of calls from a withheld number who claimed to work for the police.
The victims then met with the scammers and passed over thousands of pounds, as well as an expensive Rolex watch.
Detectives have now released an image of a man on a train they would like to speak to as part of their investigation.
The man pictured was at King’s Cross train station at around 4.33pm on 21 October 2020.
It's believed a man was travelling to Retford from London King’s Cross. He then got into a taxi to travel to Ranskill to visit one of the victims to collect their money as part of the scam.
He has been described as black, around 6ft tall, with short black hair, slim build, around early to mid-20s, wearing a blue short waterproof rain jacket and dark trousers.
Detective Sergeant Marc Lancaster, of Nottinghamshire Police's Fraud Department, is leading the investigation. He said: "These are two horrible incidents which have seen two elderly men being targeted and losing a lot of money to fraudsters.
"As part of our investigation we are keen to identify and speak to the man pictured in connection with courier fraud.
"We believe this man pictured may have information which could assist with our investigation.
"In both incidents the men have been scammed and been made to visit banks to withdraw large amounts and in one case to buy an expensive Rolex watch which was handed onto a courier as part of the scam.
"In one of the incidents the scam was spotted three days after the initial phone call by a jewellery shop owner.
"Meanwhile the second vulnerable victim told his granddaughter the details and she realised that he's been scammed, so rang Nottinghamshire Police.
"We are now urging anyone who recognises the man in the image to please come forward and help with our enquiries.
"If you can help with our investigation please call 101, quoting incident number 405 of 23 October 2020.”
Courier fraud is where criminals call someone, pretending to be a police officer or bank official.
They warn the victim that there are corrupt bank staff at the branch they use, who are intent on stealing their money, and ask them for their help.
Typically, the caller then tells the victim to withdraw a sum of money and a member of the criminal gang is sent to their home address to collect it.