The Muslim community in Des Moines, Iowa ... is diverse. The members of the four mosques here are from Yemen, Somalia, Pakistan and Bangladesh, among other nations. [But] the community is a tight-knit group. That's why what happened at their mosques here is alarming to so many of its members. That was really surprising, very sad that ... the FBI or Homeland Security would send somebody here to pretend to be Muslim and try to find out what goes on here. I feel there is no need for that," said Dr. Hamed Baig, president of the Islamic Center of Des Moines. Baig is talking about 42 year-old Arvinder Singh. Baid says he saw Singh a couple of times at his mosque. But it wasn't until recently that members of the community discovered that Singh, who was raised a Sikh, was allegedly sent into their mosques to spy for the FBI. Singh told CNN that the FBI told him, "'You look Middle Eastern, and we need your help for the war against terror.'" Singh says the FBI came to him with a simple tradeoff: We'll help you get your citizenship if you help us get some terrorists. Singh says he assumed a Muslim identity -- Rafik Alvi -- and went into the mosques pretending to be interested in converting. He says he frequented mosques all over the state but attended the four in Des Moines regularly for seven years. He says sometimes the FBI gave him pictures of persons of interest and he would confirm that they were at the mosque. On a few occasions, Singh says he taped his conversations with congregants.