on Friday.

In the 20 months since the attack, multiple independent, bipartisan and GOP-led probes already have faulted the State Department for inadequate security at the outpost, leading to four demotions. No attacker has yet been brought to justice.

Republicans say they're unsatisfied with explanations so far, and they have leveled a range of accusations against President Barack Obama, Clinton and other senior administration officials. Chief among them is that the administration misled the American people about the nature of the attack during a presidential election campaign and stonewalled congressional investigators.

Benghazi has produced 13 public hearings, the release of 25,000 pages of documents and 50 separate briefings. The select committee won't be the only inquiry, as other GOP-led congressional panels continue their investigations, including a House Oversight probe which justlast week took the extraordinary step of subpoenaing a Cabinet member, Secretary of State John Kerry. Kerry hasn't said when he might testify.

Democrats deride the effort as a conservative campaign designed to energize Republican voters in typically low-turnout midterm elections.