Personally, I feel going to the landlord before the police is the wrong approach. Sure, take notes, record the guy ranting, but when death threats by a possibly/probably unbalanced person occur, you need to consider your safety first. He can be arrested and hauled out of there for behavior like that.
He sounds like he could fly off the handle and start killing people upon very little provocation.
Anyway, that's how I see it.
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A finger in every pie.