United States military forces recently took custody of two Islamic State prisoners allegedly involved in the 2015 death of former NAU student and human rights activist Kayla Mueller according to The Washington Post. The decision follows a Turkish invasion in northeastern Syria that threatened the security of a battlefield prison, which housed Islamic State detainees.

The Washington Post reported last week that Alexanda Kotey and El Shafee Elsheikh are the only two prisoners that have been taken into United States custody, according to military officials on Oct. 9. Both men were relocated by U.S. military forces to an undisclosed location in Iraq.

“They are being held in military custody pursuant to the law of war. They have been moved out of Syria and are in a secure location,” a U.S. Defense Department official said Oct. 9 to The Washington Post.

Officials added that they are monitoring the security of five dozen other prisoners. According to a recent Time report there are more than 10,000 ISIS detainees held by Kurdish forces, of which 2,500 are considered highly dangerous foreign fighters from Europe and elsewhere.

The move follows Turkey’s government launching an offensive into northeastern Syria after President Donald Trump indicated that U.S forces would be withdrawing from the area. Guards were pulled from prisons run by Kurdish forces to deal with the Turkish invasion, according to The Washington Post.

“We have a certain number of ISIS fighters that are particularly bad, and we wanted to make sure that nothing happened with them in respect to getting out,” President Trump said at The White House Oct. 9, referring to Islamic State terrorists Kotey and Elsheikh.

“They are the worst of the worst!” Trump later tweeted Oct. 10.

Kotey and Elsheikh are two of four members of the Islamic State dubbed “the Beatles” by hostages, due to their English accents. The group is alleged to have kidnapped and murdered western hostages in Syria and are allegedly involved in the 2015 death of Mueller. Notably, “the Beatles” were also reported by The Washington Post to have been directly involved with the beheadings of journalists James Foley, Steven Sotloff and aid worker Peter Kassig in 2014.

Mohammed Emwazi, identified by U.S. intelligence as the man who killed Foley, Sotloff, Kassig and other hostages, was killed in a drone strike in 2015.

Following the broadcast beheading of the three U.S hostages, concerns arose about Mueller’s safety. Mueller was taken hostage with her boyfriend, Omar Alkhani, in August 2013 while the couple was leaving a Doctors Without Borders hospital in Aleppo, Syria. Two months later Alkhani was released. Mueller died two years later while being held hostage by the Islamic State, but the exact cause of her death was not confirmed.

Mueller grew up in Prescott and graduated from Tri-City College Prep High School in 2007. Following high school, Mueller came to NAU to study political science, graduating in just five semesters. Mueller was deeply involved in human rights programs during her time in college, and was a member of NAU’s chapter of STAND, a student anti-genocide coalition, before becoming the organizations president.

Post-graduation, Mueller continued pursuing activism in many facets, oftentimes abroad. In between her missions outside of the country, she volunteered at Northland Cares, an HIV/AIDS clinic in Prescott.

Mueller’s parents joined parents of other hostages to publish a plea when Kotey and Elsheikh were first taken into Kurdish custody in February 2018. The plea insisted that the men be tried in the U.S., or at least in a court of international justice. The Mueller’s told The Arizona Republic the prosecution may provide them closure and aid in locating and returning Mueller’s body to her family.

The criminal prosecution for Kotey and Elsheikh is contingent on evidence being released by British authorities. Following the transfer of the men into U.S. custody, Attorney General William Barr asked President Trump to prioritize securing the detention center where they are being held, to which the president immediately agreed.

When the news broke that men were taken into U.S. custody, Diane Foley, the mother of slain journalist James Foley, told The Associated Press she would like to see the prisoners prosecuted in the U.S.

“We need some semblance of justice for the horrific execution and torture of the Americans,” Foley told The Associated Press.

While Kotey and Elsheikh have yet to be prosecuted, charges related to Mueller’s captivity have already been issued. Umm Sayyaf, the wife of a senior leader for the Islamic State, Abu Sayyaf, was charged in federal court with holding Mueller hostage and contributing to the aid worker’s death.

Kotey and Elsheikh were detained with the goal of an eventual trial within the U.S. said an anonymous senior official, according to The Washington Post.