prison 监狱
in prison 在坐牢
She is in prison. 她在坐牢。
He's spent a lot of time in prison.
他坐了很久的牢。

be sent to prison 被关押
She was sent to prison for six months.
她被关了六个月。

go to prison 进监狱
She went to prison for six months.
她被关了6个月。

prisoner 犯人，囚犯
take no prisoners (为达目的）不择手段，不顾他人感受。
When he gets angry, he takes no prisoners.
他一生气，就完全不顾他人的感受。

culprit 罪犯；肇事者(someone who has done something wrong, or, a fact or situation that is the reason for something bad happening)
People are getting much fatter, and milk tea is one of the main culprits.
现在人都越来越胖了，奶茶就是元凶之一。

wrongdoer 做坏事的人，违法犯罪的人（a person who does something dishonest or illegal）
He is a wrongdoer because he cheated on his girlfriend.
他做错了事情，因为他劈腿了。