The Killing Curse doesn’t shed blood; the target simply drops dead.
The Killing Curse is characterized by a flare of green light of a very particular frequency, which consistently appears in descriptions of its use.
The Killing Curse is two words, not one.
That said, we don’t know what incantation or ritual is involved in making a horcrux. It may very well be blood magic, and use merely the word “Horcrux!”
Evidence against it being the Killing Curse:
The Killing Curse doesn’t shed blood; the target simply drops dead.
The Killing Curse is characterized by a flare of green light of a very particular frequency, which consistently appears in descriptions of its use.
The Killing Curse is two words, not one.
That said, we don’t know what incantation or ritual is involved in making a horcrux. It may very well be blood magic, and use merely the word “Horcrux!”