Former Secretary of State Hillary Clinton is set to testify Thursday before a House of Representatives committee investigating the Sept. 11, 2012 attack on the American consulate in Benghazi, Libya.

The committee, charged with investigating the government’s actions before and after the attacks, is expected to complete the investigation and  will issue a final report likely sometime in 2016.

Here is some background about the hearing today 

What happened

On Sept. 11, 2012, there were two attacks on the American compound in the Libyan city of Benghazi. On that day,  Christopher  Stevens, America’s ambassador to Libya, was in Benghazi at the temporary diplomatic mission that had been established there to build ties in the region.

Tensions in parts of the Middle East were high, and hours before the assault began in Benghazi, violence broke out in Egypt. Rioting over an anti-Muslim video made in America ended with protesters climbing the walls of the U.S. Embassy in Cairo and setting flags on fire.

1. The attack in Benghazi

Around 9:40 p.m. local time, according to a State Department's Accountability Review Board, the attacks began when  a few men scaled the wall of the compound and opened the front gate. A U.S. security officer alerted Stevens, and he and Sean Smith, a State Department employee, were taken to a safe room in the complex.

After gaining access to the grounds, the attackers set buildings on fire, including the one Stevens and Smith were in. Both were overcome by smoke and both would die of smoke inhalation.

According to investigators, Stevens was alive when he was found in the smoldering building after the attack, and was taken by Libyan civilians to a hospital where he died.

As the first of two waves of attacks was taking place, a security team from a Central Intelligence Agency annex about a mile away arrived to help. They were able to find Smith, who had died, and took his body back to the annex.

Soon after, the annex was targeted and hit with mortar fire, and there two CIA security contractors – Tyrone Woods and Glen Doherty – were killed  on the building’s rooftop.

Hours later, U.S. security officials station in Libya’s capital, Tripoli, along with a Libyan military unit rescued the remaining U.S. personnel from the site.

The attacks lasted for more than eight  hours.

2. The controversy

While the committee is looking at what allowed the attacks to happen, there are three main points they are focusing on.

-The lack of security: Clinton will be asked today to explain why in the months  leading up to the attacks, cables from Stevens to his bosses at the State Department asking for increased security in Benghazi were not heeded.

-The story: As the events of the day came to light, a “talking points” memo was prepared for lawmakers and for then-U.N. Ambassador Susan Rice. Rice was chosen to represent the  administration on Sunday news shows that  week. The edits to the CIA-produced memo that suggested the attack was in response to an anti-Muslim video produced in the United States has led some to suggest the administration attempted to cover up the fact that security was not what it should have been at the compound, and requests for more security had been ignored. The original talking points, and Rice’s comments on the Sunday news shows, suggested that protesters outside of the compound – upset over the video – were “hijacked” by extremists and joined in in the attack. First-hand reports and investigations have concluded that no street protest took place.

-Why  no military help: There were no U.S. military units that could get to Benghazi as the attacks were ongoing, investigators have determined, and the committee wants to know why no forces were available and  why it help of that kind had not been anticipated.  There has  been no evidence the military was told to stand-down, as some suggested in the  weeks and months after the  attack.

3. The investigation

The House Select Committee on Benghazi  has held three  public hearings in its 17-month history, and interviewed 54 witnesses. It has  reviewed 50,000 documents, it’s chair, Rep. Trey Gowdy, (R-S.C.), said.

4. What happens today

Today Hillary Clinton will testify before the committee. She was secretary of state when the attack happened and has been criticized for ignoring warnings of the deteriorating conditions in Libya.

According to Gowdy, the questions Clinton will face will likely be about actions taken or not taken before the attacks – such as why the requests for added security were rejected.

As for the ongoing controversy about emails Clinton sent using a private server,  Gowdy says the committee’s only interested in the ones related to Benghazi and the attacks.

5. Who is on the committee

In addition to Gowdy, Republicans Susan Brooks of Indiana, Jim Jordan of Ohio, Mike Pompeo of Kansas, Martha Roby of Alabama, Peter Roskam of Illinois and Lynn Westmoreland of Georgia. The top Democrat is Rep. Elijah Cummings of Maryland, i and he id joined by Democrats Adam Smith of Washington, Adam Schiff of California, Linda Sanchez of California and Tammy Duckworth of Illinois.

6. If you want to watch

Time: The hearings begin at  10 am. (ET)

How long: Hours. Each of the committee members – 12 of them – have 10 minutes to ask questions on a topic. The questions alternate between Republican and Democratic members. There are numerous rounds of questions scheduled.

Where you can watch it: C-SPAN3 will carry it live in its entirety. You can find the C-SPAN.org livestream here.