If Western countries were ever in denial about their citizens going abroad to fight alongside the Islamic State, as the old saying goes, “The devil is in the detail.”

Details- lots and lots of personal details of at least 22,000 ISIS recruits who have joined the terror organization in Syria and Iraq from 51 countries including the U.S., have been leaked in a series of documents.

The information, including extremists’ names, dates of birth, citizenship, phone numbers, addresses and even blood types, comes from forms that serve as admission applications foreign fighters are obligated to fill out before they are accepted.

A collection of 1736 documents portraying the 23-question application wannabe terrorists fill out was leaked by Zaman Al Wasl, a pro-opposition Syrian news website.

Many of the names, both genuine identification and their new ISIS nom-de-guerres, on the registration forms are well-known jihadis, according to Sky News, who obtained the files on a memory stick stolen by a man who goes by the name Abu Hamed, a disgruntled former head of The Islamic State’s internal security police, a high-level intel service for the terror group.

Abu Hamed, a former Free Syrian Army convert to ISIS, was responsible for the group’s most sensitive secrets and would travel with the drive so that he would not lose or forfeit it, according to Sky News.

Authorities in the West are hoping these details will offer much in terms of tracking down jihadis in the U.S., Canada, U.K, and all of Europe.

Terrorists are applying from all over the world, including applicants from Russia, Iran, Morocco, Egypt, Tunisia and Saudi Arabia.

Germany’s Federal Criminal Police Agency (BKA) and Justice Department have already confirmed the documents, and say they hope this crucial information will lead to indictments against alleged terrorists who have returned or are returning to Germany, German newspaper Süddeutsche Zeitung said, quoting Germany’s Interior Minister Thomas de Maiziere.