וְגַ֤ם דַּֽם־הַנָּקִי֙ אֲשֶׁ֣ר שָׁפָ֔ךְ וַיְמַלֵּ֥א אֶת־יְרוּשָׁלִַ֖ם דָּ֣ם נָקִ֑י וְלֹֽא־אָבָ֥ה יְהוָ֖ה לִסְלֹֽחַ׃
and also for the innocent blood that he shed; for he filled Jerusalem with innocent blood; and the LORD would not pardon.
Read Kabbalistic (mystical) interpretations of II Kings 24:4: Zohar and classical Jewish mystical sources, free online.