One of ISIS's executioners formerly participated in the flotilla to Gaza, British authorities say.
According to the UK, Alexanda Kotey, a 32-year-old man originally from London, was aboard the 2009 flotilla with former MP George Galloway.
Kotey has been identified as one of "the Beatles," four ISIS terrorists from the UK. They were led by Mohammed Emwazi, dubbed "Jihadi John," who was killed in a US drone strike last year.