Contrary to comments yesterday by a US attorney, federal agents are investigating Lance Armstrong for criminal activity, ABC News reports. "Agents are actively investigating Armstrong for obstruction, witness tampering, and intimidation," says a source. US attorney Andre Birotte, who yesterday said feds wouldn't charge Armstrong, "does not speak for the federal government as a whole," the source tells ABC, adding that Birotte isn't involved in the probe. (More Lance Armstrong stories.)