the story of a crime (1962)
The original title is История одного преступления. Apparently "Story of a crime" is considered a somewhat important short animated film, if it having its own Wikipedia article demonstrates that this is so, although I guess that's an arguable proposition.
It was the first animated short made by one Fyodor Khitruk(1917-), at the age of 45. I gather he worked as an assistant for other animation directors beforehand. (Apparently he's still around, having published a book on animation in 2008.) This is part 1, above. Part 2 is directly below.