Niko Bellic's contact at United Liberty Paper orders him to locate Dimayev using the LCPD Database and kill him during the mission "Portrait of a Killer". He is located near a small garage in East Island City, Dukes surrounded by bodyguards, creating a shield that the player has to fight through before Dimayev can be reached. Niko kills Dimayev in the gunfight. He is needed to be killed, otherwise the mission won't progress. If he is left running away, he will reach the roof and try to kill you in a last stand. If you kill him before his guards, one of them will drop his gun and you are given a chance to spare him. It's not Dimayev, however.
LCPD Database record
Place of Birth:
Linked to Russian Organized Crime
2006 - Grand Theft Auto
Immigrated to the US, possibly illegally, from Russia.
Believed to be head of a car stealing ring based in Dukes.
Wanted for questioning by the Russian government in connected with the bank rolling of terrorist activity around the Caspian Sea.