Numbers 35:33
"So ye shall not pollute the land wherein ye are: for blood it defileth the land: and the land cannot be cleansed of the blood that is shed therein, but by the blood of him that shed it."
Cross References (ranked by relevance)
And shed innocent blood, even the blood of their sons and of their daughters, whom they sacrificed unto the idols of Canaan: and the land was polluted with blood.
Whoso sheddeth man’s blood, by man shall his blood be shed: for in the image of God made he man.
And the land is defiled: therefore I do visit the iniquity thereof upon it, and the land itself vomiteth out her inhabitants.
For, behold, the LORD cometh out of his place to punish the inhabitants of the earth for their iniquity: the earth also shall disclose her blood, and shall no more cover her slain.
And also for the innocent blood that he shed: for he filled Jerusalem with innocent blood; which the LORD would not pardon.
Notwithstanding the LORD turned not from the fierceness of his great wrath, wherewith his anger was kindled against Judah, because of all the provocations that Manasseh had provoked him withal.
Now also many nations are gathered against thee, that say, Let her be defiled, and let our eye look upon Zion.
His body shall not remain all night upon the tree, but thou shalt in any wise bury him that day; (for he that is hanged is accursed of God;) that thy land be not defiled, which the LORD thy God giveth thee for an inheritance.
They joined themselves also unto Baalpeor, and ate the sacrifices of the dead.