Opening statements take place on Monday in the US federal trial of a British-born jihadist accused of hostage-taking and conspiracy to commit murder.
El Shafee Elsheikh, 33, is the last of a group of Islamic State militants – known as the Beatles for their British accents – to be brought to justice.
The group is said to have tortured and beheaded hostages in Syria, including several journalists and aid workers.
The trial, in Virginia, is expected to last three to four weeks.
Mr Elsheikh, who went to Syria in 2012, is charged with taking hostages, resulting in the deaths of four Americans – journalists James Foley and Steven Sotloff and aid workers Kayla Mueller and Peter Kassig.
He is also charged with conspiring in the deaths of the British aid workers David Haines and Alan Henning, and Japanese journalists Haruna Yukawa and Kenji Goto.
Mr Elsheikh, who was stripped of his British citizenship in 2018, denies the charges.