British-born Alexanda Kotey, a member of the infamous cell of the Islamic State responsible for the kidnapping, torturing and beheading of American, European and Japanese victims between 2012 and 2015, has pleaded guilty in a U.S. court to multiple charges linked to the killing of four American hostages.

Kotey, 37, nicknamed one of the "The Beatles" because of his British accent, was stripped of his UK citizenship in 2018, when he was captured together with another British-born suspect, El Shafee Elsheikh, by Syrian Kurdish forces in Syria.

The two were later turned over to U.S. forces in Iraq.

In October last year, both suspects pleaded not guilty to the charges moved against them. But on Thursday, Kotey pleaded guilty to murdering American journalists James Foley and Steven Sotloff and relief workers Peter Kassig and Kayla Mueller.

He now faces a life sentence without possibility to appeal for early release. He will spend the first 15 years in a U.S. prison and will then be extradited to the UK, where he faces other charges of kidnapping and murdering hostages.