Peter Kassig was an Iraq War veteran who went to Syria to volunteer at hospitals. In a profile aired by CNN in 2012, Kassig said he's an idealist who believes in hopeless causes.
Stuart Delery stayed out of the limelight even as he argued controversial cases. A recent promotion makes him the highest-ranking openly gay lawyer in the Justice Department.
The fire left three administrative buildings badly burned. The memorial marks the spot where United Flight 93 crashed during the terrorist attacks of September 11.