Police acting without the FBI’s knowledge may have inadvertently helped blow the surveillance of a terrorism suspect and compromised a bomb plot investigation at a sensitive stage by questioning an imam about him, a criminal complaint suggests. “They came to ask me about your characters,” the Muslim religious leader, Ahmad Wais Afzali, told Najibullah Zazi in a secretly recorded Sept. 11 telephone conversation. “They asked me about you guys.”

A 24-year-old Afghan man at the center of an unfolding FBI investigation into a possible U.S. terrorism cell was ordered held without bond in Colorado Monday as authorities raced to learn more about an alleged plot using hydrogen peroxide explosives and who else might have been helping to carry it out. Meanwhile, authorities in Washington and elsewhere were stepping up safety patrols on mass transit systems in response to an advisory issued in connection with the probe.

FBI agents investigating what they describe as a plot to detonate homemade bombs in the United States released documents Sunday asserting that an Aurora airport-shuttle driver admitted to al-Qaeda training and had bomb-making notes in his laptop.