Disgraced cyclist Lance Armstrong is under a criminal federal investigation for obstruction, witness tampering, and witness intimidation.
According to ABC News, federal investigators "are not concerned with the drug use, but Armstrong's behavior in trying to maintain his secret by allegedly threatening and interfering with potential witnesses."
During an interview with Oprah Winfrey last month, Armstrong admitted he used performance-enhancing drugs to win all seven of his Tour de France titles.
Federal investigators may be looking into how people like Betsey Andreu, who said she heard Armstrong admitting to a doctor that he had doped before he got testicular cancer, were treated.
Andreu has said Armstrong's henchmen left her voicemails threatening to bash her head in with a baseball bat to silence her, and Armstrong knew about the voicemails.
During his interview with Oprah, Armstrong deflected questions about Andreu, except when he said he thought he could slam Andreu as a liar solely because Andreu said Armstong called her "fat," which Armstrong denied.
Armstrong implied that even if everything Andreu was saying was true, he felt he could call her a "liar" if she got a single detail about an incident wrong.