My character received the quest to find and kill the leader of a new gang prowling around near the village of Fogelevka, and to bring the head to the chief of militia in Krasnoznamenny. The head is in Fidel's inventory, but I'm having trouble remembering who gave me the quest in the first place. I've gone down to the bunker to speak with Gennady Nikolaev, but right now the only thing he's concerned about is killing off the circus. There's also someone in the hotel behind a locked door with a very large, very tough guard in front of it.

Where is the chief of militia that wants the guy's severed head?

Yep. He's in the first building as you enter the second portion of the city. His name is Sergey Streletskiy, and it looks like he continues to give out random "Bring me the head of a bandit" quests. First time I did it, I thought it was a bug because it asked for the same exact bandit head I had just given him. I reloaded, to see if that would happen again. This time, the bandit leader was running around near the Roaring Forest. Thanks for the help!

Edit - It would be nice if the Journal/quest log gave the name of the person who gave you the quest for all of them, rather than just sometimes. Either that, or make it possible to add notes to the city maps.