Brian McNamee claims he couldn't risk lying to federal agents when asked about Roger Clemens and performance-enhancing drugs.
McNamee was a guest on "The Howard Stern Show" Monday.
"You just think of circumstances," McNamee said. "It wasn't worth that risk of that being over my head for six years -- that's the term they have to investigate you and convene a grand jury."
McNamee: I Had To Be Truthful About Clemens