David Petraeus has made a career out of serving his country. Understandably, he would probably like to fade into the wallpaper following revelations about an extramarital affair with his biographer, also married. The affair was a serious breach of trust to his family but also to his country: Secret affairs leave the participants vulnerable to blackmail, not a good position for a CIA director.

But Petraeus must fulfill at least one more duty to his country: The recently resigned intelligence chief should volunteer to testify at the upcoming congressional hearing on the Sept. 11 attack on the U.S. Consulate in Benghazi, Libya. Petraeus had conducted a personal investigation into the attack that killed Ambassador Chris Stevens and three other American, and he can almost certainly contribute to our understanding of that vexing event.

Additionally, the odd timing of his resignation, just days after the election, invites added suspicion. Petraeus must clear the air.