他保证不会让凶手逍遥法外。用英语怎么说？

他保证不会让凶手逍遥法外。

He promised that the murder would not go unpunished .

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

promised

vt.& vi. (promise的过去式或过去分词形式)，承诺，允诺，答应；v. 允诺( promise的过去式和过去分词 )，答应，有…希望，预示；

例句
They have promised to pay the arrears over the next five years...
他们保证在随后的5年内偿付逾期债款。

that

det. 那个，那；pron. 那个，那；conj. 多么，如此…以至，用于某些动词、形容词和名词后，引出各种从句；adv. 不那么，那样；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

murder

n. 谋杀，杀戮，极艰难[令人沮丧]的经历；vt. 凶杀，糟蹋，打垮；vi. 杀人；

例句
He was intent on murder and he came within an ace of succeeding.
他一心想杀人并且差点就得逞了。

would

aux. 将，将要，愿意，会，打算，大概；v. (will 的过去式，用于转述)将；

例句
I would love to go abroad this year, perhaps to the South of France.
我今年很想出国，可能是去法国南部。

not

adv. 不，[用以表示否定、否认、拒绝、禁止等]不是，几乎不，未必，没有[用于否定后面的词或短语]；

例句
It became very clear that the incident was not just an aberration, it was not just a single incident.
事实已经很清楚，这件事不是偶发的，它并不是一起孤立的事件。

go

vi. 走，离开，去做，进

例句
I would love to go abroad this year, perhaps to the South of France.
我今年很想出国，可能是去法国南部。

unpunished

adj. 未受惩罚的；

例句
The chief criminals shall be punished without fail, those who are accomplices under duress shall go unpunished and those who perform deeds of merIt'shall be rewarded.
首恶必办, 胁从不问,立功受奖.