U.S. law enforcement officials believe they may have identified the masked man seen in the ISIS video of the killing of American journalist James Foley. Also  the United Kingdom has investigative interest believing that the masked man is believed to be a British citizen who traveled overseas to engage in conflict

A U.S. official, cautioning that they are not 100% sure yet said, “they have a pretty good idea of who it may be.” The official said, “We’ve been using all means to identify the person.” That includes voice analysis and analyzing metadata from the video as well as other methods, according to the second U.S. official. The official declined to elaborate on what those other methods were.In late August, British Ambassador Peter Westmacott said his country was close to identifying the ISIS militant.

The subject is believed tied to a group of extremists based in London, the officials said. FBI agents have been working with British authorities to nail down who the subject is, a priority for both governments.

Authorities are still trying to determine the identity of the militant speaking in the video of American journalist Steven Sotloff and determine if it is the same person in the Foley video, according to one of the officials. The source said “it’s too premature” to know with any certainty just one week since the video of Sotloff’s death was published.

The source said British and American authorities would work together to find the masked man, who is believed to be in Syria.