FBI Knows Who the ISIS Executioner Is

The  knows the identity of the masked, English-speaking ISIS militant who has been videotaped apparently murdering American hostages - and believes a second man featured in the latest video from ISIS is likely from somewhere in North America, FBI Director James Comey said today.

Comey declined to reveal the name of the man, who top U.K. officials previously have saidappeared to be British. Comey told ABC News the FBI and international partners were able to identity him.

In several ISIS videos in which Western hostages appear to be beheaded, an armed militant -- possibly the same man every time -- stands beside them and delivers statements against Western actions against ISIS in Iraq. Then he takes his knife to their throats.