Late in the evening Savchenko was in his house

Late in the evening, Savchenko, who was in his house, heard a dog barking and shuffling his legs in the yard. Fearing the robbers, Savchenko lit a light, took a gun and left the room in an unlit canopy. The door from the courtyard opened, and a man appeared in the opening, as Savchenko thought, with a revolver in his hand. Savchenko shot him. Mukhin, a friend of Savchenko, was killed by a shot. There were no weapons with him.
Give a criminal assessment of Savchenko’s actions. Can they be justified by the state of necessary defense?