Why did Jack visit the tall house on the side of the hill in The Graveyard Book?

In The Graveyard Book by Neil Gaiman, the book begins by detailing a “man named Jack” and his entry into a house to kill its inhabitants. When Jack enters the house, he leaves the door slightly open. He kills the woman, the man, and the older child; all that is left for him to do is kill the baby.
Readers get the impression that the man named Jack is a hired killer, as he is described as a “professional” in the text. Jack also has an extraordinary sense of smell and can track people by their smell. When he gets to the baby’s room, he realizes the baby is no longer in his crib.
The book then describes what happened when the baby escaped his crib and made his way down the stairs and out the door that the man named Jack left open. The baby wanders up the hill and into the graveyard. Jack follows his smell up the hill and encounters the “caretaker,” who seems to be a ghost or at least some kind of otherworldly creature. The caretaker makes Jack leave the graveyard and tells him he won’t remember the conversation with him—and he doesn’t. The baby stays in the graveyard and grows up to be the character Bod.
Later in the book, we find out Jack was supposed to kill the family, especially the baby, because of a prophecy stating the baby would put an end to the secret society called the "Jacks of All Trades" of which Jack is a member.
Works Cited:
Gaiman, Neil. The Graveyard Book. Harper Collins, 2008.