Well I suppose the it IS possible depending on the make and model of the weapon and the level of maintenance.
We are assuming this was a LONG time ago going by how long the guy has actually been training, being a petty criminal the weapon and ammunition could well been cheap and quite old. The user may have had the weapon for years without proper maintenance, they may not have understood how to properly make ready a pistol for firing (which is very unlikely but lots of people do make silly assumptions).
I have seen magazines that have been left loaded for far too long lose all spring tension and malfunction, especialy with low grade manufacturing but in this case the top round would most likely still be fed to the chamber and you would have a stoppage on the second round rather than first.
The 2 most likely explanations in my opinion are
1- The assailant didnt intent to murder someone for no reason and was just getting his kicks from dominating someone and seeing the expression on his face.
2- The guy is indeed making things up.
Again we are back to the stage hypnotism concept. I have a friend who does this proffessionaly and he also only uses about 40% of people for his act and volunteers who want it to work are normaly the ones on whom it does work, VERY effectivly. I do have a friend who used an instant induction technique in a real self protection situation but I have a feeling the aggressor was just more weirded out than anything else!
Its all a bit too 'Men Who Stare At Goats' for me!