"So this guy is going to become one of the biggest mass murdererd ever... possibly the biggest (what is the estimated record for killing people?)"
I think it might be held by the priests of the Aztecs. I was watching Jean Rollin's film The Two Orphan Vampires this morning, and they said that over 100,000 people had lined up at the foot of an Aztec pyramid for the largest ritual sacrifice in history in 1488 at a 3 day festival. So if that is true, then it must be 100,000 and held by Aztec priests.
My advice is not to take history lessons from a schlockmeister!