Britain’s Supreme Court on Wednesday lifted a stay barring U.K. authorities from providing evidence to the U.S. in the case of two alleged ISIS execution squad members dubbed “The Beatles.”

The ruling clears a critical hurdle in the American effort to prosecute the two men, El Shafee Elsheikh and Alexanda Kotey.

Elsheikh and Kotey are accused of being involved in the killing of American hostages, including the journalists James Foley and Steven Sotloff, and the kidnapping and detention of an aid worker, Kayla Mueller. The pair of British-born ISIS militants are being held in U.S. military custody in Iraq.

Read more: NBC News