TUNIS & KASSERINE, Tunisia — When Jamel Ben Moussa, 29, joined the Islamic State (IS) at the end of 2014, he said he did so “to help the Syrian people.” The young Tunisian man had watched sleekly produced recruitment videos posted online “showing women and children being slaughtered by Syrian regime forces. I had to do something.” Moussa made his way to Libya, flew to Turkey, then crossed the border into the jihadi “caliphate” from the Turkish province of Gaziantep. He insisted that he received “no assistance” from any Turkish officials, only from smugglers and IS operatives.

The first months at a training camp in the Syrian town of al-Rai “were really exciting,” Moussa told Al-Monitor in a Skype interview from the northern Syrian town of Derik. He was given a nom de guerre: Abu Serra al-Tunisi. But he grew disillusioned as he witnessed IS’ atrocities. “They were killing the wrong people, like my friends, like civilians," he said. "I wanted to leave."

He tried to flee numerous times and finally succeeded in October, turning himself in to the Syrian Democratic Forces (SDF) in Deir ez-Zor. He is now being held at a detention facility run by the SDF, the US-led coalition’s top ally against IS, with the jihadis now on the brink of defeat. The SDF facilitated and sat in on his interview with Al-Monitor.

Moussa, who speaks good English — he learned it at school — is among thousands of Tunisians who ended up in IS. p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Helvetica; -webkit-text-stroke: #000000} span.s1 {font-kerning: none} Estimates vary, and it's impossible to verify, but 3,000 to 6,000 is the range most commonly touted, making Tunisia one of the countries with the highest number of recruits per capita. SDF officials told Al-Monitor that it currently has 150 Tunisians in its custody, a figure Moussa confirmed. Most hail from the capital, Tunis, he said.