He is first met by Scar when he made his way to the supposed patrol that needed ammunition, then tasked Scar to bring the PDA of the patrol leader, where he finally realized Lingov's treachery. He also gives the mission that requires the termination of the mercenaries in the Dark valley which is also needed if the player wants to join Freedom. The player must talk to Chekhov after finishing these missions if he decides to join the Freedom faction.
If the player completes his job to drive the mercenaries from the Dark Valley, he will give a USB flash drive with upgrades for an SVU sniper rifle that can be traded to Yar for at least 6750 rubles.
His future fate is unknown as he was not present nor mentioned in the events of Shadow of Chernobyl or Call of Pripyat. Although there is a stash that can be collected in Shadow of Chernobyl titled 'Supplies of the leader of Freedom' that is located in a Pripyat supermarket. It suggests that Chekhov may have been the sole survivor of a Freedom squad after passing through the Brain Scorcher, but according to the stash information "Everything went not the way it was planned", and Chekhov died in Pripyat soon after.
In the English version of Clear Sky, Chekhov is voiced by Steven Blum, famous for voicing Spike Spiegel from Cowboy Bebop and Grunt from Mass Effect. He also provides the voice for Freedom technician Yar and Clear Sky trader V. I. Suslov.