Charge : Suspect initially wanted to plan attack on September 11 , authorities say . Affidavit : Teen accused in Texas bomb plot wrote violent comments on extremist Web site . Hosam Maher Husein Smadi accused of plotting to bomb Dallas skyscraper . Smadi told lies to undercover FBI agents , authorities say .
NEW : Suspect initially wanted to stage attack on September 11 , authorities say . Affidavit : Teen accused in Texas bomb plot wrote violent posts on extremist Web site . Hosam Maher Husein Smadi accused of plotting to bomb Dallas skyscraper . Smadi told plans to undercover FBI agents , authorities say .