A 70-year-old woman has been arrested on suspicion of fraud and money offences.
She 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 yesterday's search-and-arrest operation.
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."
It urged anyone with concerns to report them to Action Fraud by phoning 0300 123 2040 or call police on the non-emergency number 101.