Anti-terrorism police are, for the second day, questioning the three suspects arrested in an al Shabaab swoop in the posh Rossyln estate in Gigiri.
Tom James, 32, a staff member of M&C Saatchi communication, was arrested with two Somali women on Tuesday.
They were nabbed at a house in Gigiri on suspicion that they recruited and radicalised youths to join the terror group.
The two women have been identified as
Sheikhdoa and Kenyan
The three suspects spent the night in police custody after their arrest by a team of investigators from the Flying Squad, Special Crime Prevention Unit and NIS.
They were handed over to the Anti-Terror Police Unit for further questioning.
Police said they found items including training literature and books in the raid.