Mark Harmon had fans fearing the worst when
The National ENQUIRER caught the actor looking gaunt after becoming a recluse in his Hollywood home. But now
RadarOnline has uncovered
the secret behind the "NCIS" star's health crisis. Mark fears the kind of sudden heart attack that killed his father, but an insider revealed: “He isn’t sick. About a year ago, he had surgery on his knee. It was an old football injury.”