Detica is an external company that provides fraud detection services to RBS Group. It uses customer information like email, address, phone number, and transaction data to create social networks and identify potential fraud risks. Detica's NetReveal system ranks these networks based on factors like cash cycling, confirmed fraud, suspected fraud, large networks, and cheque spending. The document then lists various tools used in fraud investigations, including profiling customers, searching internal records, reviewing account notes and transactions, checking identity documents, and creating investigation notes with recommendations.