A 70-year-old woman has been arrested on suspicion of fraud and money offences.
The pensioner was detained in west Belfast. Her arrest came after a bank in Coleraine alerted police to a suspicious withdrawal from a 74-year-old man's account.
The man had fallen victim to a PPI scam and had posted thousands of pounds in cash to addresses in London and Belfast.
On Monday, he posted cash to an address in Belfast.
That prompted Thursday's search-and-arrest operation in the west of the city.
A PSNI statement said: "Tackling fraudulent behaviour is a priority for police and this is an excellent example of officers providing the personal service the community desires.
"Guarding your personal and banking details is essential. Never disclose them to any unauthorised person. If you have received a call of this kind or are concerned by the intent of unsolicited calls, emails or letters then please report it to Action Fraud via their website www.actionfraud.police.uk or by phoning 0300 123 2040, or call police on the non-emergency number 101."