President Donald Trump celebrated the killing of Islamic State (ISIS) leader Abu Bakr al-Baghdadi by U.S. forces on Sunday. Still, many high profile Americans died under al-Baghdadi’s reign before U.S. forces were able to kill him.

Here are four Americans who were killed when the ISIS leader was in power.

James Foley, a Celebrated American Journalist Who Relied on His Catholic Faith

James Foley was beheaded by the order of al-Baghdadi in 2014, while he worked as a freelance video journalist in northern Syria. Born on October 18, 1973, in Evanston, Illinois, he was the oldest of five children who graduated from Marquette University in Milwaukee, Wisconsin, in 1996.

He later got a degree in journalism from Medill School of Journalism at Northwestern and began a career reporting in conflict zones, from Afghanistan to Libya, and then Syria.

In 2011, Colonel Muammar Gaddafi detained Foley while he was reporting in Libya. During that time, Foley relied on his Catholic faith while in captivity, especially his praying of the rosary.

Foley eventually wrote a letter to Marquette explaining how the university helped him keep the faith using the rosary:

I began to pray the rosary. It was what my mother and grandmother would have prayed. I said 10 Hail Marys between each Our Father. It took a long time, almost an hour to count 100 Hail Marys off on my knuckles. And it helped to keep my mind focused.

After Foley was released from captivity 44 days later, he began to travel in and out of northern Syria as a video journalist. He was kidnapped again on November 22, 2012, in northern Syria before ISIS beheaded him on August 19, 2014, in Syria’s Raqqa region.

2. Kayla Mueller, a Humanitarian Who Was Kept Captive by al-Baghdadi

Kayla Mueller, of Prescott, Arizona, was doing humanitarian work in Syria when she was kidnapped in 2013. She was travelling with Syrian contractors for Doctors without Borders on the way back to Turkey after installing communications equipment at a hospital when armed ISIS fighters stopped the group.

The others taken prisoner with Mueller were eventually released, but ISIS thought she was a spy and kept her captive in various locations until her death.

Mueller was imprisoned for a time by Islamic State financier Abu Sayyaf and his wife Umm Sayyaf. Abu was eventually killed in a 2015 raid, while Umm was captured by FBI officials and charged with imprisoning and torturing Mueller. According to an FBI affidavit, al-Baghdadi personally raped Mueller while she was in the Sayyaf’s custody.

The Islamic State leader also referred to Mueller as his “property” and “wife.”

Mueller was killed in the city of Raqqa, the Syrian capital of ISIS, in February 2015.

National Security Adviser Robert O’Brien told NBC’s Meet the Press Sunday morning that U.S. forces named the mission to take out al-Baghdadi after Mueller.

3. Steven Sotloff, a Hardcore American Journalist with a “Gentle Soul”

Steven Sotloff asked the tough questions until the very end of his life, when he was beheaded by ISIS militants in 2014.

While in captivity, Sotloff asked al-Baghdadi to debate Islam, saying, “Woe to you. You said the month of Ramadan is the month of mercy. Where is your mercy?”

Sotloff—who reported for TIME, the National Interest, and Foreign Policy— was captured by ISIS in August 2013 while he was reporting on the civil war in Syria between Islamist forces and people loyal to Syrian President Bashar al-Assad.

Sotloff was reportedly executed by the same jihadi that slaughtered James Foley, according to the Guardian. The journalist’s mother, Shirley Sotloff, released a video begging al-Baghdadi to release her son.

“My son Steven is in your hands. You the caliph, can grant amnesty. I ask you please to release my child. I ask you to use your authority to spare his life,” she said at the time.

Family and friends of Sotloff called him a “gentle soul” who enjoyed watching American football and South Park in his free time.

4. Peter Kassig, an American Aid Worker and Army Ranger Who Converted to Islam

Kassig deployed to Iraq as an Army Ranger in 2007, but returned to the region on humanitarian grounds to help Syrian Civil War refugees in a Lebanese hospital.

“We each get one life and that’s it. The way I saw it, I didn’t have a choice. This is what I was put here to do. I guess I am just a hopeless romantic, and I am an idealist, and I believe in hopeless causes,” Kassig told CNN in a 2012 interview.

Kassig is said to have disappeared soon after while working in Syria, although a report from the New York Times said that he converted to Islam and changed his name to Abdul-Rahman.

It is unclear whether he was forced to convert to Islam or chose to convert in the hopes that ISIS militants would save his life. In October 2014, Kassig’s parents begged ISIS to release their son.

“We implore his captors to show mercy, and use their power to let our son go,” Kassig’s father stated.

Kassig’s mother, who was wearing a hijab, stated, “We implore those who are holding you to show mercy, and use their power to let you go.”

ISIS later claimed responsibility for Kassig’s graphic beheading in 2014.

Trump named Kassig— along with Foley, Mueller, and Sotloff— in his statement on Sunday about the casualties suffered under al-Baghdadi.