The killing was the act of a madman.

这起凶杀案是一个疯子所为。

《牛津词典》

"He drives like a madman," was all the information he vouchsafed.

“他开车时像个疯子，”这是他给予的全部信息。

《柯林斯英汉双解大词典》

He drove like a madman.

他像疯了似的驾车飞驰。

《牛津词典》

and insanity incites to action. With no definite plan and acting like a madman, Murlock ran quickly to the wall.

VOA: special.2009.10.31

And Roosevelt's increasingly progressive policies in nineteen thirty-five made many richer Americans fear that the president was a socialist, a dictator or a madman.

VOA: special.2011.03.31

watch a madman seize a subway train.

VOA: special.2009.06.12

I've been traveling like a madman lately and can vouch for full planes and busy airports.

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Julie: Tell the police that there is a madman running around and shooting people.

CNN: 'Mom, don't panic ... but there's a gunman going loose here'

The question currently asked about the Kaczynski trial is how a court can judge a madman.

ECONOMIST: The last outsider