“We have an open criminal investigation,” Holder said. “And those who would perpetrate such acts need to understand something. This
Holder added, "We will not forget what happened and people will be held accountable -- one way or the other."
Foley was seen in the video kneeling in orange garb in a desert scene with a tall masked man in black wielding a knife by his side. The man, according to U.S. and British authorities, is believed to be a British citizen.
British newspapers said the executioner ran a squad of other Britons who have been holding foreign captives at the behest of the Islamic State, apparently in the Syrian stronghold of Raqqa. The man called himself "John" and apparently served as a negotiator in releasing other hostages. One of those ex-hostages later said they called the group the "Beatles" because of their British accents.
Foley's parents said they had been working with the FBI to find and free their son, an effort that helped start what Holder on Thursday called "an open investigation and one that we will be pursuing very vigorously."
Asked if he had watched the video, the attorney general said, "I don't want to comment on that."
Federal officials have jurisdiction in the case because Foley was an American citizen, much as in the federal probe into the 2011 raid at the U.S. compound in Benghazi that took four American lives, including that of the U.S. ambassador to Libya.