An Estonian citizen, named Vladimir, has been arrested for fighting for the Kremlin-backed separatists, and is likely to be extradited to Ukraine.

On Monday, Harju County Court put the man on provisional custody, and if he is extradited to Ukraine, he will be the first Estonian citizen to be sent abroad on terrorism charges, Eesti Päevaleht reported.

Following an investigation with the Ukrainian prosecution and other institutions, the Estonian Internal Security Services apprehended the 34-year-old on the border check-point in Narva in February, with the daily saying he was on his way, through Russia, to the east of Ukraine, where he had previously completed two stretches.

Vladimir, who had illegal firearms and ammunition with him, had previously fought in Luhansk in June and November of 2014, spending around a month in the conflict zone on both occasions.

“According to the evidence, the Estonian citizen Vladimir was part of a unit assigned to convoy and guard prisoners and it is not ruled out that he also took part in battles against the Ukrainian state,” Prosecutor Steven-Hristo Evestus said.

Vladimir had previously killed an ethnic Russian man in Estonia, allegedly for crossing a street too slowly. He fled Estonia and joined the French Foreign Legion, before returning to Estonia and serving his sentence.

So far, two people from Estonia have gone to fight in the Middle East. Robert Lindmets left Estonia in 2014 to join Kurdish forces battling the Islamic State. Ivan, now Abdurrahman, Sazanakov left Estonia in 2013 with his wife and two daughters and joined the Islamic State. He initially posted pictures on social media sites of him handling weapons, but has now deleted his accounts.

According to the daily, a Swedish-Estonian, David Eriksson, fought with the Azov battalion, a volunteer unit with the Ukrainian government for a year. He said he wanted to protect Estonia bu fighting in Ukraine.