Ambassador Chris Stevens and three other Americans - information management officer Sean Smith, and former Navy SEALs Glen Doherty and Tyrone Woods - were killed in a six-hour, commando-style attack on the US Mission in the Libyan city on September 11, for which Al Qaeda in North Africa and Islamist militia Ansar al-Sharia were implicated.
Eric Nordstrom, a diplomatic security officer who was the regional security officer in Libya, has since given testimony that he and the late ambassador had repeatedly asked to increase security at the embassy in the months leading up to the attack, but said that their pleas fell on deaf ears as the situation in the country deteriorated.
The ambassador himself detailed 'never-ending security concerns' in an e-mail.
http://www.dailymail.co.uk/news/article-2373113/Aftermath-Benghazi-New-details-emerge-horrific-attack-killed-U-S-ambassador-support-Al-Qaeda-grows-war-ravaged-Libya.html