DAVOS, January 19. /TASS/. Turkey’s authorities will do everything they can not to leave any stone unturned while investigating the murder of Russian Ambassador Andrei Karlov, which took place on December 19, 2016, Turkey's Deputy Prime Minister Mehmet Simsek told TASS on Thursday on the sidelines of the World Economic Forum in Davos.

"There is a joint investigation with Russian authorities and we are doing everything we can, we are not going to leave any stone unturned," Simsek said. He added that Turkey was ready "to uncover everything that is behind" the ambassador’s murder.

Russia’s Ambassador to Turkey, Andrei Karlov, was gunned down while he was delivering a speech at a photo exhibition. According to Turkey’s authorities, the attacker, an off-duty police officer named Mevlut Mert Altintas, was immediately neutralized by security forces. Russia’s foreign ministry officially declared the ambassador’s murder a terrorist attack, the Investigative Committee opened a criminal case labeling Karlov’s assassination an act of international terrorism. Andrei Karlov was posthumously awarded the title of the Hero of Russia.

On Thursday, Turkey’s Anadolu news agency reported that two more suspects, police officer Sercan Basar and businessman Enes Asim Silin had been arrested over the Russian ambassador’s murder case. According to investigators, Basar was the murderer’s mentor and rented an apartment in Ankara for him.

Lawyer Serkan O. and police officer Hasan T. have been released after testifying but a travel ban has been issued.