Complex sentence: He was killed by Libyan militiamen in an attack on the U.S. consulate while he was visiting Benghazi on September 11 2012, reportedly by protesters enraged over the film "Innocence of Muslims".
Split into simpler sentences: He was killed by Libyan militiamen in an attack on the U.S. consulate while he was visiting Benghazi on September 11 2012. The attackers were reportedly the protesters enraged over the film "Innocence of Muslims".