He was a notorious mass murderer.

他是恶名昭彰的刽子手。

AIDS is a mass murderer.

艾滋病是个杀人狂。

She deserves compassion not a mass murderer.

我女儿值得同情，而不是一个凶残的杀手。

So what kind of family produces a mass murderer?

那么，是什么家庭产生了杀人如麻的刽子手呢？

He once mass murderer, everyone who saw him very afraid.

他曾经杀人如麻，对敌人好不客气，见过他的人都很害怕。