David Haines Beheading Video
A video purportedly showing threats being made to a man Islamic State (IS) named as David Haines by a masked IS fighter in an unknown location in this still image from video released by Islamic State September 2, 2014. REUTERS/Islamic State via Reuters TV

FBI Director James Comey said on Thursday that the intelligence agency already knows the identity of Jihadist John, the hooded man who had beheaded American journalists James Foley and Steve Sotloff, and British aid worker David Haines.

However, he did not disclose to media the name or nationality of the militant, although previous reports from British intelligence indicated he could be Abdel-Majed Abdel Bary, a former British rapper.

Comey's revelation is the latest in unhooding Jihadist John after the British ambassador to the US said in August that UK was also close to identifying the notorious decapitator.

To know the identity of the beheading suspect, US spy plane M15 piloted by British aviators flew over Britain to monitor telephone conversations and computer signals. The operations also helped identify the people with whom the jihadists communicates. The technology could detect heat from a keyboard whenever a button is pressed. The signals and date are sent to the US for analysis.

The technology could track the computer password of Jihadist John because of the unique heat signature it generates.

The Daily Mail sad that Jihadist John is from a South London suburb, about 10 miles from Central London. Another jihadist, identified as Junaid Hussian, has been tracked to Birmingham. Hussain is suspected as being one of the jihadists named after the popular 1960s Brit boy band Beatles.

Authorities in Rome are also looking for Federico Motka, an Italian who was hostaged together with Haines, so he could help confirm the identity of Jihadist John. Motka was released in May after being held by the Islamic State (IS) for 14 months because of an alleged payment by the Italian government of a €6 million ransom.

The IS has threatened to kill Alan Henning, a British cab driver, while on, Wednesday, it killed French Herve Gourdel, captured in Algeria, as retaliation from the French air raids in Iraq.

Read: Islamic State: After France Rejects Call To Stop Air Raids In Iraq, IS Beheads Frenchman Herve Gourdel

While the authorities are using voice-recognition technology to confirm who Jihadist John is, facial-recognition technology could also help, according to this video.

YouTube/Sky News