TT #391 · Parashas Shoftim · Seventh Aliyah · Passuk 21:08
Atone for Your people Yisrael whom You have redeemed, O Eternal, and do not place innocent blood in the midst of Your people Yisrael. And the blood shall be atoned for them.
Torah Temimah points to Sifrei Devarim 210.
TT lemma: דָּם נָקִי.
English: ‘Innocent blood’ – the blood of one killed without judgment.
Derash defining the innocent blood (Sifrei) — it is blood for which no human court has yet exacted justice.
The prayer asks that the blood of a person killed without judicial process not remain as guilt upon Yisrael.