What is the legend of Ossip Bernstein, who supposedly played chess to save his life? Wikipedia article reads as following:

A famous story goes that in 1918, after the October Revolution, Bernstein was arrested in Odessa by the Cheka (Bolshevik secret police). He was ordered to be shot by a firing squad because he was a legal advisor to bankers. As the firing squad lined up, a superior officer asked to see the list of prisoners' names. Discovering the name of Ossip Bernstein, he was asked whether he was the famous chess master. Not satisfied with Bernstein's affirmative reply, the officer made Bernstein play a game with him. If Bernstein lost or drew, he would be shot. Bernstein won in short order and was released. He escaped on a British ship and settled in Paris.

Is this story entirely true? Any sources are there to support it?
The written sources appear to be:

An obituary on Bernstein by Edward Lasker (a friend of Bernstein) in the April 1963 issue of Chess Review, which is described in the link below, including a scan of the 1963 article itself: http://jewishchesshistory.blogspot.com/2009/09/alekhine-escaping-execution-definite.html

However, the US Chess Federation has made it also available on their site on page 104: http://uscf1-nyc1.aodhosting.com/CL-AND-CR-ALL/CR-ALL/CR1963/CR1963_04.pdf

A book by Arnold Denker, mentioned in the Wikipedia article itself, 'The Bobby Fischer I knew and Other Stories'. Denker seems to indicate that he also heard the story from Bernstein himself and that he always believed it.