The accused, Rajendra and Poonam, had allegedly duped people on the pretext of doubling their money and then fled to Dehradun after amassing the money, said a senior police officer.
They had "duped" 15 persons in 2013 but police kept a track and through technical surveillance, it was found that they are in Dehradun, he said.
Yesterday, their location was found to be in Najafgarh area of south west Delhi and they were arrested, he added.