Attorney General Eric Holder threatened the Islamic State of Iraq and Syria with the long arm of the U.S. justice system Thursday, vowing to hold American journalist James Foley’s killers accountable.

“[Those] who would perpetrate such acts need to understand something,” Holder said. “This Justice Department, this Department of Defense, this nation – we have long memories and our reach is very wide. We will not forget what happened, and people will be held accountable, one way or the other.”

Speaking at a press conference announcing a $17 billion settlement with Bank of America, Holder also addressed Foley’s slaying. Although he didn’t refer directly to ISIS, he said the Justice Department has begun an “open criminal investigation” into Foley’s killing and said the department will “vigorously” conduct it.

Holder also praised Foley and his work as a “symbol of what’s right about the United States” and said his “heart goes out to” his parents who are showing remarkable composure in the face of their loss.

Foley went missing in Syria two years ago. ISIS circulated a video of his beheading Tuesday that U.S. authorities have confirmed as authentic. The Obama administration announced Wednesday night that U.S. special operators tried to rescue him earlier this summer but failed because he and other hostages were not located where intelligence officials believed them to be.