1)what reason does the intruder give for his intensions to murder gerrad?

2)how does gerrad suceed in outwitting the intruder?

1) The intruder says that he has already killed someone and killing Gerrard wont make any difference as he cannot be hanged twice.
2)Gerrard says that he is also a criminal who has killed a person and is hiding from the cops. This makes the intruder believe him.