One year ago, two diplomatic compounds came under attack in Benghazi, Libya. Four Americans were killed including Ambassador Chris Stevens. Here is a look at those events and the political fallout that occurred in Washington. (The Washington Post)

House Republicans will begin their promised fall assault on the Obama administration’s conduct before, during and after the Sept. 11, 2012, terrorist attack in Benghazi, Libya, with the publication Monday of a report updating their investigation of the incident and a hearing Wednesday with testimony from a high-ranking State Department official.

The report, prepared by majority staff for House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.), focuses on what it calls “shortcomings” in the Accountability Review Board investigation of the attack in which J. Christopher Stevens, the U.S. ambassador to Libya, and three security officials were killed.

Most pointedly, it asks why the ARB, which was convened by then-Secretary of State Hillary Rodham Clinton but acted independently of the State Department, held only four mid-level officials accountable for security lapses at the Benghazi site and “downplayed the importance of decisions made at senior levels of the Department,” including by Clinton.

Virtually all the issues raised in the report have been examined at previous hearings, although Issa has alleged that the State Department and the CIA — in charge of a second Benghazi facility attacked the same night — have withheld key documents and prevented some officials from testifying or speaking in private to committee investigators.

In a statement Sunday night, Douglas Frantz, the assistant secretary of state for communications, said that “the idea that facts are being hidden and people shielded from questioning is wrong on its face.” Calling the response to the Benghazi attacks by the administration and the ARB “thorough and transparent,” the statement said that “twisting the facts to advance a political agenda does a disservice to those who lost their lives and those who have devoted the past year to understanding what happened” and making sure it does not happen again.

The administration has said that no one has been coerced not to testify, although it has resisted allowing diplomatic security agents present on the night of the attack to appear before Issa’s committee on the grounds that it would compromise their testimony in future criminal proceedings against the perpetrators. The FBI has said it is investigating the attacks and has issued several sealed indictments against Libyans. But no arrests have been made.

The State Department and the CIA have denied Issa’s assertion that employees have been polygraphed to ensure that they have not cooperated with his panel.

The report, a draft of which was provided by the committee to The Washington Post on the eve of its release, concludes that the ARB procedure was less than impartial because its chairman, retired senior diplomat Thomas Pickering, was predisposed to favor the State Department and selected review board members who shared his views.

Issa has subpoenaed all internal work products of the ARB, including witness statements, notes and report drafts. The State Department has asked Issa to reconsider the subpoena, saying that the ARB report speaks for itself and that the request for internal documents is unprecedented and unnecessary.

In particular, the committee report asks why no blame accrued to Patrick Kennedy, the undersecretary of state for management, who it said was responsible for decisions that left the State Department facility in Benghazi in place throughout 2012 as a “temporary mission” without sufficient security.

It quotes testimony from committee witnesses who said Kennedy was in the chain of command that decided not to retain a small team of Special Operations troops that had been on loan to the embassy in Tripoli and not to increase the number of diplomatic security agents in Benghazi from three to five.

The report suggests, as Republicans have previously, that approval of heightened security in Benghazi, despite escalating threats, was denied for budgetary reasons and because it would have undermined official administration policy that conditions in Libya were becoming more stable.

Pickering and his ARB co-chairman, retired Adm. Mike Mullen, are to testify before Issa’s committee Thursday. Kennedy is scheduled as the sole witness in a Wednesday hearing of the House Foreign Affairs Committee. A committee statement noted that, following ARB recommendations, only four State Department employees were placed on administrative leave for actions surrounding the Benghazi attack and that all four have been reassigned to new positions in the department.

“This hearing will examine why no one inside the State Department has yet been held accountable for the failures and deficiencies identified,” the committee statement said.