Alparslan Çelik, a Turkish national who allegedly murdered a Russian pilot whose plane was shot down by Turkish fighter planes, may face prison after prosecutors reopened the case. Çelik walked free in May after prosecutors dropped charges against him following a one-month detention.The chief prosecutor's office in the western city of İzmir reopened charges against Çelik in the light of new evidence, this time concerning the killing of another Russian soldier who was sent to the area to retrieve the pilots in the downed jet. Çelik, an ultranationalist militant fighting alongside Syrian rebels, was near the area where the Su-24 bomber crashed after Turkish military shot down the Russian fighter jet upon its violation of Turkish airspace during Russian airstrikes targeting rebels.Çelik was detained in İzmir in April along with several others, after a tip-off to the police about "armed men in a restaurant." Police detained him for violation of the firearms law for carrying unlicensed weapons, and a later probe into his role in the killing of pilot Oleg Peshkov was dismissed due to lack of evidence.Prosecutors said in a statement that after examining Russian media reports and "open intelligence sources," these revealed that two Russian airmen died in the November 2015 incident, with a second victim aboard a Russian helicopter dispatched to the area to retrieve the Su-24 pilots, and Çelik was with the group that fired on the helicopter. Çelik told prosecutors that he had urged the other fighters not to fire at the helicopter, but prosecutors said evidence showed that the group had repeatedly fired at the helicopter, and this finding necessitated a re-investigation of Alparslan Çelik's role in the killing.The reopening of the case comes at a time of an anticipated thaw in Turkish-Russian relations months after the plane crisis.Diplomatic relations between Moscow and Ankara soured following the incident.The first sign of thaw came when President Recep Tayyip Erdoğan sent a letter earlier this month to Russian President Vladimir Putin to celebrate Russia Day, the national holiday celebrating the Russian Federation's post-Soviet constitution. Some interpreted the letter as an important step toward normalizing the broken ties.