In the WaPo’s story identifying Jihadi John as Mohammed Emwazi, they noted that the FBI intimated it had ID ISIL’s executioner as far back as February.

Authorities have used a variety of investigative techniques, including voice analysis and interviews with former hostages, to try to identify Jihadi John. James B. Comey, the director of the FBI, said in September — only a month after the Briton was seen in a video killing American journalist James Foley — that officials believed they had succeeded.

In a Telegraph piece explaining how the WaPo had IDed Emwazi, Adam Goldman suggests he and his colleagues repeated that approach.

Former hostages said that the Islamic State killer spoke fluent Arabic, a hint that he was not from Britain’s large Pakistani or Bangladeshi communities.

He made his captives watch online videos from al-Shabaab, the Somali terror group, which suggested he may have had an interest in jihad in east Africa before heading to Syria.

“I was trying to pick up pieces of information, data points, scraps,” said Adam Goldman, the Washington Post reporter who broke the story with his colleague Souad Mekhennet. “It was hard, man. People were tight-lipped about this.”

When Mr Goldman finally closed in on the name of Mohammed Emwazi, a Kuwaiti-born British citizen who grew up in west London, two things quickly became evident.

The first was that the name on its own would shed little light on the identity of the man who taunted the West in Isil’s gruesome videos. Emwazi had basically none of the internet presence you would expect from a man in his mid-twenties. No Facebook account, no Twitter, no digital trace.

“The trail was thin. Which was odd because in this day and age if you’re 26 years old you’re all over the internet,” said Mr Goldman. Emwazi’s computer skills, honed at the University of Westminster, may have helped him scrub his record.

In that piece, Goldman also made clear that officials in both the US and UK knew who Emwazi was, but weren’t sharing.

The original WaPo piece also makes clear they relied, in part, on help from CagePrisoners’ Asim Qureshi. As I noted the other day, CagePrisoners has got a great deal of documentation on Emwazi’s early run-ins with the British security state, some of which is now coming out in stories.

In short, people knew, and a number of WaPo journalists were also able to learn who Jihadi John is. And they did so largely by talking to people who had met or known him — classic HUMINT.

Which is why I find this story so odd. Exclusive!! Jihadi John exposed himself via SIGINT!

Mohammed Emwazi, 26, now the world’s most-wanted man after beheading British and US hostages, had been on a shortlist of suspects.

But the crucial piece of the jigsaw fell into place when when Emwazi used a laptop in Syria to download web design software which was being offered on a free trial.

Instead of buying the software with a credit card, he used a student code from London’s Westminster University when he studied computer technology.

The number contained unique information which gave his date of birth, what he studied, and where, and information on his student loan.

Sources revealed the download singled him out as being in the right place and time to be the killer.

The information was passed back through the intelligence chain and further matches showed he was the murderer.

An intelligence source said last night: “In today’s electronic age of social media and technology, we chase the digital footprint before we chase the person.

British intelligence sources are now claiming that the SIGINT hunt for Emwazi preceded the HUMINT one, and also claiming that a SIGINT clue — and the related SIGINT trail that clue uncovered — provided the breakthrough in IDing him.

Which is almost certainly bullshit.

But notable bullshit, for two reasons. First, because the current story — that the UK lost Emwazi — poses really big problems for the dragnet. Because if someone like Emwazi, whom MI5 had been chasing for years, can simply disappear, only to reappear as the man beheading western journalists (though technically, the videos never show him doing so), then it suggests the entire dragnet is least effective when it is most needed. The Express’ ill-defined sources appear to want to tell a story about SIGINT succeeded rather then explain how it is that SIGINT failed (at least according to the story getting told publicly).

Mind you, I’m not entirely convinced Emwazi did disappear. But if he didn’t, that raises some other questions. Questions heightened by the role of CagePrisoners, as well. Remember, the Brits arrested Moazzam Begg for travel it had pre-approved to Syria in 2012, holding him from February to October 2014, when they finally admitted the British government had known of his trip, precisely the period when Jihadi John came into US consciousness.

I suspect both CagePrisoners and British intelligence are trying to spin this, in this case by focusing on SIGINT rather than HUMINT which clearly led to Emwazi.