Sforno on Genesis 9:9/ספורנו על בראשית ט׳:ט׳

1ואני הנני מקים את בריתי, this promise is conditional on man keeping his part of the bargain, bringing murderers to justice. If, however, innocent blood will be shed in the manner it had been before the deluge, this may lead to destruction of the earth (not necessarily by water). This is what is meant in Numbers 35,33 הדם הוא יחניף את הארץ ולארץ לא יכופר לדם אשר שפך בה כי אם בדם שפכו “for blood turns the earth into a hypocrite and there will be no atonement for the land except through the blood of him who has spilled it.”