Former CIA director David Petraeus has begun his testimony before Congress about the deadly September attack on the U.S. consulate in Benghazi, Libya.

The retired general is providing details of the attack and the initial U.S. response to lawmakers in both the House and Senate intelligence committees, in closed-door hearings Friday.

U.S. Ambassador Christopher Stevens and three other Americans were killed in the attack. Many lawmakers are concerned about whether there was adequate security at the consulate, and if the Obama administration later attempted to hide information to avoid embarrassment before the November 6 presidential election.

On Thursday, lawmakers said Petraeus traveled to Libya after the attack and interviewed people about what happened in Benghazi.

Petraeus has made few public appearances since he resigned as CIA chief last week, after an FBI investigation uncovered an extramarital affair with his biographer, Paula Broadwell. Reuters news says lawmakers may ask Petraeus if the affair had any impact on national security.

Attorney General Eric Holder said Thursday that he felt “very secure” that there was no national security breach in the Petraeus scandal.

Holder said that if the investigation uncovered any security threat, he would have informed the president and Congress.

In another development, House Foreign Affairs Committee chairwoman Ileana Ros-Lehtinen said Secretary of State Hillary Clinton will testify before a committee next month.