Alexanda Kotey, 34, and El Shafee Elsheikh, 29, were the last two members of the cell to remain at large. They were part of a four-person cell which gained a reputation for beheading hostages and torture.
The group included Mohammed Emwazi - "Jihadi John" - who was killed in a United States air strike in 2015. The SDF turned over the suspects to American Special Operations forces, officials said, who confirmed their identities with biometric measurements including fingerprinting. Aine Davis, the fourth member, was detained in Turkey in 2015 and convicted on terror charges a year ago. All four had lived in west London. They subjected western hostages they guarded in Syria to constant beatings.
It went on: "As a guard for the cell, Kotey likely engaged in the group's executions and exceptionally cruel torture methods, including electronic shock and waterboarding". The Times report indicated the two men were not yet in U.S. military custody and the USA justice department did not immediately respond to questions over whether they would seek to prosecute the men in federal court.
"Their crimes are beyond imagination".
It remains unclear exactly when Kotey and Elsheikh were captured, but American officials were informed in mid-January that the duo might have been detained by the SDF. They could be put on trial in the United States, since they were allegedly involved in the killing of U.S. hostages - but there may be some in the Trump administration who would like to send them to Guantanamo Bay.
- Aine Davis: Grew up in Hammersmith, West London, the son of a school dinner lady and a shop assistant who worked in John Lewis, favorite department store of the middle classes. A father-of-two and a convert to Islam in his late teens or early 20s, the U.S. identified him as a cell member in January 2017.
"I got a call late last night to say that they had been captured and the first thought was relief, finally to know that the people that were involved in my dad's murder have been caught and will sort of serve some justice", she told ITV's Good Morning Britain.
The US official did not give any information on the condition of the two or what would happen to them.
Despite the fact the cell murdered two Britons - Mr Haines and fellow aid worker Alan Henning, the security source said it was "pretty unlikely" the men would be brought to the UK.
USA officials had sought to keep the capture of the two British suspects under wraps to allow analysts more time to pursue the intelligence leads developed from their detention and prepare raids against unsuspecting ISIS targets.
Its fall led to the collapse of IS in Syria, as the last remnants of the once powerful militia fought on in a slither of land along the Euphrates River or fled to Turkey or other parts of Syria. ISIS have officially announced his death.
Vile extremist Abu Bakr al-Baghdadi declared the formation of the caliphate at a mosque in Mosul in 2014.
Ringleader Emwazi was killed in a drone strike in 2015 and Davis is in jail in Turkey after being convicted previous year on terrorism charges.