On June 6, a roadside bomb exploded near the U.S. compound in Benghazi, hurting no one but blasting a large hole in a wall of the compound.

The threats continued for U.S. officials and diplomats from other countries -- but security staffing remained unchanged.

The ambassador is missing

But now, there was no time to fret about woeful security.

Black smoke was filling up the safe area.

Stevens, Smith and the security officer crawled to a bathroom, hoping to open a window.

The security officer placed towels under the bathroom door and flung open the panes.

It made things worse.

The open window pulled more smoke into the bathroom, making breathing impossible.

Despite the explosions outside, they would have to flee the safe area, the officer thought. The smoke had choked out the lights. They were in total darkness.

The officer left the bathroom, crawled through a hallway, banging on the floor and yelling that the ambassador and Smith follow him.

He slipped though another window and collapsed in an enclosed patio area.

And then he noticed it.

Stevens and Smith were not there.

The officer slipped back through the window several times, even though the intruders were still shooting at him.

The smoke and heat was unbearable. He could not find either man.

He used a ladder to climb to the roof of the villa and radioed for help.

He had been in the smoky room for so long he could hardly speak. It took some time for the officers on the other end of the line to understand what he was saying.

He did not have Smith, he said. And the ambassador is missing.

The battle at the Annex

Three other security officers had barricaded themselves in another building when the siege began.

Once the first wave of attackers seemed to retreat, the officers got out of their "defensive" positions and drove an armored car to the villa. They found their colleague on the roof, vomiting, about to pass out.

The three officers crawled through the smoke inside.

They found Smith. They dragged his body out. But they were too late.

A team, from a nearby U.S. facility called the Annex, arrived and helped search for Stevens. They could not find him.