He lied to get citizenship, that should be enough to revoke it surely? "A 92-year-old man who has admitted being a former Nazi death squad member has won a court victory in Canada, fending off the latest of several efforts to revoke his citizenship. Canada has revoked his citizenship three times since 1995 but each time it has been overturned on appeal, the latest ruling being made on Thursday. Helmut Oberlander says he was forced to act as a translator for the WWII squad. He says he did not participate in atrocities and was conscripted. The Supreme Court in Ottawa on Thursday ruled that the Canadian government must prove he was a willing participant in the eastern Europe death squad in order to deport him from the country." http://www.bbc.co.uk/news/world-us-canada-36738564
Wait, he says he has nothing to do with it. Case closed. He only just admitted to being a member of an Einsatz group. No biggie. I'm sure in his duties as just a "translator" he never relayed orders that were horrific at all.
There are statutes of limitations for most crimes, but not for war crimes. Probably he can't be punished for lying because it's too late, the statute of limitations in this case has expired long time ago. He can be punished for a war crime, but it has to be proven first.