George killed his wife with a knife, leaving no trace and no witnesses.

Rİddle: George killed his wife with a knife, leaving no trace and no witnesses.
He returns home. An hour later the police call to tell him that his wife has been murdered and asked him to come at crime scene straight away.
As soon as he arrives, he is arrested.

How did the police know he did it?

Answer: Because, how did he know where the crime scene was?

or

Doesn’t say that the police didn’t tell him where the crime scene was… Not enough information.