Been closed for two years. That perp is dead.

已经结案两年了，凶手已经死了。

Hence a final argument against perp walks: they can be risky for prosecutors.

于是对示罪行的最后驳斥是：对检方不利。

Yet when Mahone sees that the car brought to him is a perp transport, he knows that there is no deal.

但当马宏看到他要坐的车是押送犯人的，他就明白其实根本就没什么会面。

The "perp walk" was singled out as a humiliating breach of the principle of the presumption of innocence.

“游街示众”被指是对无罪假定原则的可耻背叛。

Anyway, that's where the perp tried to clean up his victim's blood, but some invisible traces of it remain behind.

不管怎么说，犯人回尽力清理掉被害者的血迹，但是总有一些看不见的痕迹遗留了下来。