Nov. 15, 2012 -- Declaring it the first step in a long fact-finding mission, the Senate Intelligence Committees met for just under four hours today, hearing testimony from acting CIA director Mike Morell and Director of National Intelligence James Clapper, among others, about the Sept. 11 attack on the U.S. consulate in Benghazi, Libya.
On Friday morning, former CIA director David Petraeus is set to head to Capitol Hill to testify before the Senate and House intelligence committees about the attack on Benghazi, which led to multiple deaths, including that of Ambassador Chris Stevens.
During the closed-door briefing today, the committee members saw a film put together by the National Counterterrorism Center of the events in Benghazi. Also testifying today were FBI Deputy Director Sean Joyce, Under Secretary of State for Management Pat Kennedy, and National Counterterrorism Center Director Matthew Olsen.
"The film is a composite from a number of sources. It is real-time and does begin from when before the incident started and it goes through the incident and the exodus," said Sen. Dianne Feinstein, D-Calif., chairwoman of the Senate Intelligence Committee.
She added that the footage includes video shot from an unmanned aerial vehicle. But she did not answer whether the video showed Ambassador Chris Stevens, who was killed in the assault on the compound.
Petraeus's testimony is much anticipated.
"Director Petraeus went to Tripoli," Feinstein said. "He interviewed many people, as I understand it, that were involved and so the opportunity to get his views is very important."
Feinstein would not comment on the CIA's inspector general investigation into Petraeus' conduct regarding an extramarital affair with Paula Broadwell.
"The purpose of this hearing is Benghazi," Feinstein said of Friday's hearing with Petraeus. "We're not going into the FBI investigation or the inspector general or anything else. This is Benghazi."
Petraeus, who resigned last week after disclosing an extramarital affair, is expected to defend the CIA's actions during the attack that killed Stevens and three other Americans.
The retired Army general, who once commanded U.S. forces in Afghanistan, reportedly is eager to set out a timeline of events leading up to and during the deadly attack.
Spokesmen for the committee have said that the hearing will be closed to the public. Petraeus is not expected to discuss his resignation or the affair with Broadwell.
The week after next, the committee will resume with another two full hearings. Feinstein predicted that the committee will then have an open, public hearing .
"Gosh, we know mistakes were made," said Sen. Saxby Chambliss, R-Ga., ranking member of the committee. "At the end of the day, our committee is going to get to the bottom of this."
Adm. William H. McRaven, the head of U.S. Special Operations Command and the planner of the raid that killed Osama bin Laden in 2010, on Wednesday night called Petraeus "an American hero." The praise came at The Hero Summit, an event honoring the military sponsored by Newsweek-Daily Beast.
"[Petraeus ] was the finest general I ever worked for, period." McRaven said. "I don't condone what he did, because Holly Petraeus is also a great American hero."
During the interview with Charlie Rose, McRaven also touched on Gen. John Allen, the commander of U.S. forces in Afghanistan and the second top military official, who has become embroiled on the Petraeus scandal for his relationship with Florida socialite Jill Kelley, who received threatening emails from Broadwell. McRaven said he believes Allen's veracity will shine through.
Allen, a four-star Marine general, is being investigated by the Pentagon's inspector general for "potentially inappropriate" emails with Kelley, a Tampa, Fla.-area military supporter.
"[Allen is] the finest officer in the U.S. military right now, and he is a man of incredible integrity, and I think the facts will bear that out," McRaven said.
President Obama said earlier this week that he continues to have "faith" in Allen, according to White House Press Secretary Jay Carney.
FBI Vet Who Started Petraeus Email Probe ID'd
A new piece of the Petraeus case puzzle fell into place overnight with the identification of the FBI agent who pushed so hard to open the investigation into the emails sent by Broadwell that ultimately led to the discovery of the Petraeus' extramarital affair.
In May, Kelley began to get a series of emails that made her think someone was stalking her and her friend Petraeus, then the director of the CIA. Kelley then went to an FBI agent she knew personally, Fred Humphries, whose lawyer told ABC News he was the agent who helped launch the investigation and then later went to Congress when he thought there was a cover-up.
"If we hadn't had an individual that apparently believed in right and wrong with no gray, we may never have gotten to where we are in the case today," former FBI special agent and ABC News consultant Brad Garrett told "Good Morning America."
The FBI did not tell the White House about Petraeus' affair with Broadwell until the day after the election, even though agents knew about it about a month earlier.
FBI Director Robert Mueller went to Capitol Hill Wednesday to defend the bureau's handling of the case at the same time that the president was saying he is "withholding judgment" while waiting for a full explanation, and has full confidence in the FBI.
As FBI agents continue to investigate the classified documents found in Broadwell's computer, the President said he knew of no security lapse. Obama told a news conference Wednesday that he has "no evidence at this point."
The Department of Defense has revoked Broadwell's security clearance. And at MacDill Air Force Base in Tampa, officials have revoked the special access clearance once given to Kelley.
Since he was named in the unfolding scandal, Agent Humphries, 47, has only been briefly seen, speeding from his home to avoid the media.
ABC News' Martha Raddatz and Brian Ross contribute to this report