JUDY WOODRUFF: Hillary Clinton returned to Capitol Hill today to defend her actions as secretary of state during the 2012 attack on a diplomatic outpost in Libya.

The Republican-led Select Committee on Benghazi is investigating the attack on a U.S. Consulate, which left four Americans dead, including Ambassador Chris Stevens.

Political director Lisa Desjardins reports on the contentious hearing.

LISA DESJARDINS: It was a full-blown Capitol Hill spectacle, with one of the longest lines in recent years, and reporters crushing forward to try to get inside.

Republican Committee Chairman Trey Gowdy began by defending the Benghazi investigation.

REP. TREY GOWDY (R), South Carolina: Madam Secretary, not a single member of this committee signed up to investigate you or your e-mail. We signed up to investigate, and therefore honor, the lives of four people that we sent into a dangerous country to represent us, and to do everything we can to prevent it from happening to others.

LISA DESJARDINS: Former Secretary of State Hillary Clinton in turn started with a slow, deliberate tone.

HILLARY RODHAM CLINTON, Democratic Presidential Candidate: As secretary of state, I had the honor to lead and the responsibility to support nearly 70,000 diplomats and development experts across the globe.

Losing any one of them, as we did in Iraq, Afghanistan, Mexico, Haiti, and Libya, during my tenure was deeply painful for our entire State Department and USAID family and for me personally. I traveled to 112 countries as secretary of state. Every time I did, I felt great pride and honor representing the country that I love.

LISA DESJARDINS: Soon, though, Republican Susan Brooks of Indiana launched what would become a theme: Was Clinton paying enough attention to Benghazi? Brooks pointed to a small stack of Clinton's Benghazi e-mails the year of the attack, 2012, and a larger one from the year before.

REP. SUSAN BROOKS (R), Indiana: There are 795 e-mails in this pile. We have counted them. There's 67 e-mails in this pile in 2012.

And I'm troubled by what I see here. In this pile in 2011, I see daily updates, sometimes hourly updates from your staff about Benghazi and Chris Stevens.

When I look at this pile in 2012, I only see a handful of e-mails to you from your senior staff about Benghazi. And let me just share for you in your records that we have reviewed, there is not one e-mail to you or from you in 2012 when an explosive device went off at our compound in April.

HILLARY RODHAM CLINTON: Well, Congresswoman, I didn't conduct most of the business that I did on behalf of our country on e-mail. I conducted it in meetings.

I read massive amounts of memos, a great deal of classified information. I made a lot of secure phone calls. I was in and out of the White House all the time. There were a lot of things that happened that I was aware of and that I was reacting to.

If you were to be in my office in the State Department, I didn't have a computer. I didn't do the vast majority of my work on e-mail.

LISA DESJARDINS: But another Republican, Georgia's Lynn Westmoreland, wasn't satisfied with Clinton's defense.

REP. LYNN WESTMORELAND (R), Georgia: You knew about these two incidents that have been mentioned previously. It's not a matter if you knew about them. It's a matter of what you did about them. And, to us, the answer to that is nothing.

HILLARY RODHAM CLINTON: The experts, who I have the greatest confidence in, and who have been through so many difficult positions, because practically all of them had rotated through Afghanistan, Pakistan, Iraq, Yemen, other places, they were the ones making the assessment. No one ever came to me and said, we should shut down our compound in Benghazi.

REP. LYNN WESTMORELAND: I'm not saying I'm not saying shut it down. I'm just saying protect it.

HILLARY RODHAM CLINTON: Right.

LISA DESJARDINS: Republican Jim Jordan of Ohio pushed on whether Clinton knew the attack was planned by terrorists, but still allowed official U.S. statements to claim it was a spontaneous anti-American mob.

REP. JIM JORDAN (R), Ohio: Why didn't you just speak plain to the American people?

HILLARY RODHAM CLINTON: I did state clearly and I said it again in more detail the next morning, as did the president. I'm sorry that it doesn't fit your narrative, Congressman. I can only tell you what the facts were.

LISA DESJARDINS: Clinton's fellow Democrats sounded their own theme, arguing that she's the victim of a partisan political witch-hunt.

REP. ADAM SMITH (D), Washington: Even today's hearing, not a single solitary thing that hasn't already been discussed repeatedly. So we have learned absolutely nothing. The question is, have we found anything substantively that tells us something different about what happened in Benghazi? And the answer to that question is no.

LISA DESJARDINS: The partisan tension bubbled over, as Republicans repeatedly asked about e-mails about Libya from longtime Clinton friend and previous committee witness Sidney Blumenthal.

REP. ELIJAH CUMMINGS (D), Maryland: Will the gentleman yield? Will the gentleman yield?

LISA DESJARDINS: Ranking Democrat Elijah Cummings broke in to accuse Chairman Gowdy of distorting information.

REP. ELIJAH CUMMINGS: These facts directly contradict the statements you made on national television this past Sunday.

REP. TREY GOWDY: No, that's — no, sir, with all due respect, they do not. With that, we're adjourned.

LISA DESJARDINS: In the end, this longest hearing yet on the Benghazi attacks may not have done much to satisfy either party. The committee aims to finish its investigation by January.

For the PBS NewsHour, I'm Lisa Desjardins.