Nabil Al-Marabh, 34, a Middle Eastern man on the FBI’s list of people wanted for questioning in the terrorism investigation, was captured outside Chicago at a convenience store where he was working as a clerk, the FBI said Thursday. He is being held on an Immigration and Naturalization Service request and a warrant issued in Boston for assault with a knife, according to a bureau spokesman. Walid Beitouni, owner of the convenience store, 7 Days Food & Liquor, told the Associated Press that Al-Marabh had worked there several days. Beitouni admitted that he was stunned Wednesday night when FBI agents entered the store with guns drawn and arrested his employee. He said he asked what the clerk had done and was told by an agent: “He’s involved in something you don’t want to know about.” Beitouni said Al-Marabh had told him he was living with an uncle nearby and had shown him a Canadian driver’s license. He said the man had been asking for a job for several weeks. Federal agents reportedly had been looking for Al-Marabh since at least Monday. That day, they raided a Detroit house with Al-Marabh’s name on the mailbox and arrested three men after discovering false visas, passports and other ID, as well as what appeared to be a diagram of an airport flight line.