I did a bit of cursory poking around.
What I found from primary sources, easily, was plenty of documentation that he was a pretty nasty guy.
What I did not find, readily, were first-hand accounts of the vast numbers of people that he's supposedly responsible for murdering.
It is extremely clear that he committed terrific atrocities.
That seems perfectly, and easily substantiated.
I think it would take a lot more digging though, to find primary accounts for the vast genocidal numbers he's supposedly responsible for.
I'm not defending him.
He may actually be responsible for killing 3 million people.
It's just that when I see HUGE numbers thrown around, I like to see evidence for those numbers.
We have to remember, every time a historical figure is either deified of vilified, there are CURRENT POLITICAL MOVEMENTS which gain some variety of ENORMOUS BENEFIT. Therefore, we should always be a bit cautious spreading information we haven't checked.