Lenta.ru reports on the killing. This Batman (not to be confused with Batman bin Suparman or Batman, Turkey) was Alexander Bednov, organizer of a militia unit in the Luhansk (or Lugansk) People’s Republic — one of the breakaway portions of Ukraine (or the Ukraine). The unit was also called the “Batman” unit. Here’s part of the Lenta.ru report:

The fighters of the “Batman” battalion accused the head of the self-announced Lugansk People’s Republic, Igor Plotnitsky, of organizing the killing of their commander Alexander Bednov. This is reported on a page in the social network “VKontakte” [“In contact"].
According to battalion members, Bednov, known also as Batman, died January 1 as a result of the attack on their convoy. The prosecutor’s office states that the commander was killed while he was being arrested.
“Alexander Alexandrovich Bednov, better known under the nickname ‘Batman’ and as the creator of the battalion [fast-reaction group Batman] died on the morning of January 1, 2015 during an attack on his convoy….”

I say “The Carpenter” — while stressing the “allegedly” part — because that would be Plotnitsky’s supervillain name; “Plotnik” means carpenter.