Croatian citizen Tomislav Salopek has been beheaded by ISIS, according to photos published by the group on social media. The pictures were uploaded on the morning of August 12 but it’s unclear exactly when the execution took place. The 31-year-old had been held by the group since July 22 when he was kidnapped close to Cairo, Egypt. His death, ISIS says, was due to Croatia’s role in the war against the Islamic State.

Here’s what you need to know:

1. Gruesome Photos Showed Salopek’s Decapitated Body

In a previous video featuring Salopek, it was said that Salopek would die unless Egypt released “muslim women” from jail in 48 hours from the clip’s appearance. Salopek was shown in a yellow jumpsuit, kneeling down in front of a masked knife-wielding terrorist. The clip of Salopek begging for his life has been removed from YouTube due to a violation of the site’s terms of service. The video was released on August 5. The photos of Salopek were verified by the terrorism watchdog SITE Intel.

In the images released by ISIS, there are two photoshopped insets from Egyptian newspapers, one highlighting Croatia’s support for Egypt in the War on Terror, the other Croatia’s support of Kurdish rebels. The Independent reports that the Egyptian interior ministry has not yet confirmed Salopek’s death and was working to confirm the authenticity of the photos. The Croatian foreign ministry said the same though the BBC reports that the country’s prime minister is preparing a statement on the execution. A spokesman for Salopek’s employers said “we fear the the worst,” reports the Associated Press.

2. He Was the First Civilian Hostage to Be Taken by ISIS in Egypt

Salopek had been working in Cairo, the Egyptian capital, as a surveyor for the French company CGG. Reuters reported two days after he was taken that his car was stopped by militants while Salopek was traveling to work. The specific group responsible for his capture were ISIS-Egyptian offshoot Wilyat Sina. He’s the first civilian to be taken hostage by the group.

In a brief statement, CGG said “His car was stopped by an armed group who forced the driver to leave the car and then took off in an unknown direction.” General Geoscience (CGG) specializes in the exploration and production of gas and oil. Al Arabiya reports that Salopek’s kidnapping “rattled foreigners working for multinational companies and underscored the jihadists’ reach.”

3. The Family of One Female Islamist Prisoner Expressed Their Disgust at Salopek’s Death

Speaking to the Associated Press, Doaa el-Taweel, sister of Esraa el-Taweel, who has been in an Egyptian prison for two months, referred to “the life of an innocent man who is not responsible for … (Egyptian government) detainees …” In an open letter in July 2015, el-Taweel wrote about her arrest. She’s accused of being a member of the banned Muslim Brotherhood. She said, “I spent 15 days at the national security premises, listening to interrogations, hearing sounds of torture, and men crying loudly…I was the only lady there, fifteen days with my eyes were covered.”

4. He Was Experienced With Working in the Middle East

According to LinkedIn, Salopek worked in Iraq from 2012-2013, living in Kurdistan. His page says that he’s been with CGG since December 2014 having previously worked for Nageco in Libya. Prior to that, Salopek spent a year working in the Czech Republic for a different company. On his LinkedIn, Salopek states that he’s fluent in English and has basic Arabic.

On his Facebook page he’s shown to be married to a woman named Natasa. The couple have two young children, a boy and a girl, together. They live in the western part of the country. He married his wife in November 2007.

5. ISIS Wants Muslims in the Balkan Countries to Rise Up & Enforce Sharia Law

CNN reported in February 2015 that Croatia was considered a part of the coalition to battle ISIS. Also in the coalition are Croatia’s neighbors Serbia and the predominantly Muslim country of Bosnia and Herzegovina. In July 2015, an ISIS video encouraged Muslims in the Balkan countries to take up arms and establish Sharia Law in the region. Meanwhile in March 2014, Brown Moses reported that ISIS had taken control and was using Croatian weaponry the group hijacked from convoys meant for the Free Syrian Army.