Bezler's father, Nikolai Bezler (or Mykola Byezlyer), was an ethnic German (original spelling of his surname in German - Besler), his mother was an ethnic Ukrainian, but he considers himself Russian.
He served in the Soviet Army in Afghanistan (1983–84) and in Russia's 1990s wars to defeat Chechnya's independence movement. He was awarded the Order of the Red Star. In 1994-97 Bezler studied at the Dzerzhinsky Military Academy. (It is possible that this reference is to the FSB Academy.)
The Security Service of Ukraine (SBU) claims that until 2002 he served in detachments of the Russian General Staff GRU retiring as a lieutenant colonel. In 2002 Bezler moved to Ukraine.
According to Ukrainian officials, in February 2014 he was contacted by agents of the GRU. Complying with their instructions, Bezler supposedly moved to Crimea where he participated in number of violent events connected with taking over of military installations and government facilities. In April 2014, as a member of a diversion group, Bezler helped take over the SBU headquarters in Donetsk Oblast and the MVS district department in Horlivka.
On April 14, 2014, a YouTube video showed a man claiming to be a lieutenant colonel of the Russian army addressing police officers at the pro-Russian-held Horlivka police station and naming a new police chief.
The man was subsequently identified as Bezler. Ukraine accused him and Igor Strelkov of orchestrating the killing of Horlivka deputy Volodymyr Ivanovych Rybak. Bezler denies his involvement.
On July 17, 2014, 2 minutes before the crash of Malaysia Airlines Boeing 777-200 MH17, Bezler received a phone call from an informant called "Naimanets" suggesting that a "high flying bird" was heading his way. At 4:40 p.m. Kyiv time, 20 minutes after the crash of Malaysia Airlines Boeing 777-200 MH17, Bezler reports to a person identified by Ukraine’s SBU as Vasili Geranin, a colonel in the main intelligence department of the general headquarters of the armed forces of the Russian Federation, regarding the shooting down of a plane. Bezler has said that the talk had really taken place but that he had talked about a Ukrainian attack aircraft shot down by the militia a day before the Malaysian airliner crash.
Shaun Walker, a reporter for The Guardian, claims that Bezler "is regarded as something of a loose cannon, even by other rebels, who speak about him in hushed tones." When Walker interviewed Bezler with the hope of asking him about the MH17 crash, Bezler reportedly bragged that he summarily executes some of the combatants he captures: "Those who are fighting with the Ukrainian army, we keep as prisoners. Those who are fighting with volunteer battalions, we question them and then shoot them on the spot. Why should we show any pity to them?... You should see what they have done to my people. They chop off their heads and shit in the helmets! They are fascists! So why should we stand on ceremony with them? Questioning, an execution, that’s it. I will hang those fuckers from lampposts!". According to Walker, when Bezler saw the journalists recording this conversation, he ordered, "Burn their notebooks! Seize their electronics! Search everything for compromising material and then destroy it! If you find anything, execute them as spies!... Don’t think for one minute I will hesitate to have you shot."
In November 2014 Bezler disappeared from public sight in Donbass and speculations about his death was circulated by some Ukrainian media (including a version that he was assassinated by Russian special services). Luhansk People's Republic representatives admitted "he left the Donbass" but rejected the claims about his death. A video appeared on YouTube by end of November in which Bezler appeared, explaining he's alive and in Ukraine's Poltava Oblast.
On December 19, 2014, Bezler was placed on the Specially Designated Nationals List by the U.S Office of Foreign Assets Control (OFAC). This placement prohibits U.S. persons from undertaking any business with him without first obtaining a license from OFAC.
Early March 2016 Bezler claimed in a post on (social network) VK that he "always was and still am a supporter of a single sovereign federal Ukraine, but without Nazis and obsessive nationalism" and had never been a supporter of the recreation of New Russia. He also stated that the Donetsk People's Republic had become a "Banana republic" with a stealing leadership.