A London-based extremist group may be the key to finding the Islamic State militant in the execution video of American journalist James Foley.

CNN reports that U.S. and British officials are working together because they believe the militant may be tied to the London group, but what would happen if the link is confirmed remains unclear.

The beheading of two American journalists, which began with James Foley followed by Steven Sotloff, has been deemed, by the public, the declaration of war by IS (formerly ISIS) on the U.S.

The information of identifying a potential suspect is the latest development in media reports, which first indicated aggressive pursuit of the man's identity by British officials in late August.

British Ambassador Peter Westmacott said in an Aug. 26 interview with CNN that the U.K. was close to identifying the suspect. But officials still have not been able to determine if the same man they are seeking is the one that appeared in the video of Sotloff's killing.

"This person is in an environment that's highly dangerous. He could meet his demise on the battlefield," an official told CNN about Foley's killer, but the prospect of bringing the individual in for a trial was also not ruled out.

Initial reports pointed at a British rapper as the possible executioner, Fox reported.

Abdel Majed Abdel Bary, 23, was the suspect identified as possibly being the killer by British officials.

He used to perform as L Jinney and appeared on BBC Radio in 2012, Gawker reported.

A sound expert had compared the footage of Foley's killing with Bary's rap songs and told The Independent that it sounded very similar to Bary, according to Gawker.

In addition, there have been social media posts from Bary in Syria, holding a head, and authorities know that he left home declaring he was leaving for the sake of Allah.

Friends have also said he became radicalized, Gawker reported.