A Tajik man, Abdul Ahad Rustam Nazarov, who joined Islamic State said many foreigners who joined them in the caliphate in Iraq and Syria were jailed or killed.
The 28-year-old, who once drove a taxi in Moscow, said they were killed or jailed for trying to leave the Islamic State in Iraq and Syria (ISIS).
He said IS militants locked the fighters in cars and fired at them when they tried to leave them to stop them to surrender to the Syrian Democratic Forces.
He handed himself over to the Syrian Democratic Forces (SDF).
The SDF is a U.S.-backed group fighting against the Islamic State in Iraq and Syria.
Tajikistan has offered amnesty to those who quit Islamic State and return home.
Nazarov says he never fought for Islamic State (IS).
He said, he was jailed three times for trying to leave and he did not make a pledge of allegiance to the caliphate, adding, foreign men who traveled to Syria were immediately taken to Mosul in Iraq for military training.
He said, some were executed because they were not ready to commit to IS.
Thousands of men from Central Asia have travelled to Syria and Iraq to join Islamic State since 2014.
He said, most of the snipers in IS ranks from Chechnya died in battle in Mosul, Baiji and Raqqa.