Whoever touches a dead body, the body of a human being who dies, and does not purify himself, defiles the Mishkan of the Lord, and that person shall be cut off from Yisrael; because the water of sprinkling was not thrown upon him, he shall be unclean; his uncleanness is still upon him.
Torah Temimah: Chullin 72a — From where do we know that a revi’is of blood that comes from a corpse conveys impurity? As it is said “whoever touches a dead body in the soul of a human”; what is a “soul of a human” that conveys impurity? You must say this is a revi’is of blood.
English: From where do we know that a revi’is of blood that comes from a corpse conveys impurity? As it is said “whoever touches a dead body in the soul of a human”; what is a “soul of a human” that conveys impurity? You must say this is a revi’is of blood.
Identification of “nefesh adam” as a revi’is of blood.
A quantity of a revi’is of blood from a corpse is itself a source of corpse impurity.