Answer:
Gerrard was a very intelligent person and could convince people easily.
His words were very convincing and melodramatic and theatrical to convince anyone.
When the intruder tried to kill him and stay as an imposter, Gerrard said it was a foolish idea, and better plans can be worked out from saving the person from police arrest.
He locked the person in the room and went out so that the police could not find him.
Step-by-step explanation: