[mainepatsfan]

Hasn't Putin denied the Soviet responsibility for this?

[lizol]

He'd love to probably, but it's to late, as Gorbachev and Yeltsin formally admitted it in the beginning of 90's.

What Putinist Russia's authorities do now is refusing to recognize Katyn massacre as a genocide and war crime.

In their opinion it was a series of 20.000 single murders.

What's the goal for such a stance?
"Ordinary" murder is subject to time limitation, and after some time has passed - the killer can't be prosecuted.

It's different with perpetrators of genocide and war crimes - as according to international rules such crimes are not subject to time limitation (see Nazi war criminals, being chased around the world regardless of the fact, that they are in their 80's-90's).