The Federal Bureau of Investigation is reportedly considering those Americans who harbor " conspiracy theories " about the September 11,2001 attacks as a potential terrorist.The FBI has instructed local police departments about the case in a circular, Digital Journal reported. “The memo thus adds 9/11-official-story skeptics to a growing list of targets described by federal law enforcement to be security threats, such as those who express "libertarian philosophies," "Second Amendment-oriented views," interest in "self-sufficiency," "fears of Big Brother or big government," and "Declarations of Constitutional rights and civil liberties,"” according to the report. A new poll conducted by YouGov showed that one in two Americans have doubts about the US government’s account of 9/11. After viewing video footage of World Trade Center Building 7’s collapse, 46 percent suspect that it was caused by a controlled demolition, according to the survey that was released on the 12th anniversary of the event. American people are still questioning the government’s version of the tragic incident 12 years after the attacks left 3,000 people dead when hijacked jets crashed into the World Trade Center. Last week, a new billboard was erected in New York City to urge people to "Rethink 9/11." The massive billboard was installed in the Times Square.