The suspicions of a sharp-eyed Westcountry police officer has helped uncover what has turned out to be a multimillion-pound national scam involving investment in rare earth metals.
Devon and Cornwall Police have now issued a warning about the con in an effort to safeguard elderly investors from further loss.
Detectives from the Plymouth-based Financial Investigation Unit were alerted to the fraud after a police constable made a routine visit to a man in his 80s regarding a completely separate matter.
As the officer was about to leave, she became aware the elderly man was about to head off to the bank to pay in a five-figure sum to secure an investment.
A brief chat about the investment aroused her suspicions and she passed on her concerns to detectives from the Financial Investigation Unit.
Devon and Cornwall Police are now liaising with investigators from City of London Police, who have taken the lead role in the nationwide scam that has since emerged.
Police sources said the number of victims across the country could run into the thousands.
Police said the fraud involves victims being 'cold called' and persuaded to invest substantial amounts of money in rare earth metal oxides.
The investment potential is either hugely exaggerated or it involves a worthless commodity.
Initial investigations have led officers to examine firms across the UK as well as in other countries.
A police spokesman said: "The victim tends to be elderly and contact is usually made by telephone. Following pressurised selling, considerable amounts of personal savings are deposited into seemingly bona fide company bank accounts in the hope of a future substantial return, which in fact never materialises.
"Nationally, the fraud totals millions of pounds, and the number of victims falls into thousands, with five victims identified in Devon and Cornwall."
While the investigation is ongoing, the force is warning the public to be aware of the scam.
Detective Sergeant Mark Newnham, of the Financial Investigation Unit, said: "The extent of this scam is huge and anyone could become a victim of persistent fraudsters.
"Although there are bona fide companies who deal legitimately in metal investments, this particular fraud involves investment in very poor-valued or worthless commodities.
"Genuine companies do not 'cold call' and use intimidating and persuasive tactics and I would urge anyone who is contacted out of the blue regarding such investments to think very carefully.
"Do not agree to invest on a whim without making basic checks into the company".
Anyone who thinks they may have been a victim of this fraud can contact Fraud Action on 0300 123 2040.
Alternatively a report can be made by emailing email@example.com