Brain teaser 1

A man killed his wife for he was not sure of her fidelity. He stabbed her in the heart with a knife. To cover up his crime, he pushed her body in his car. He drove a few miles and then threw her body in an alley. He carefully wiped his finger prints and threw the knife on the crime scene.

Then, he drove back to his home. After an hour, he received a call from the local sheriff. The sheriff told him that his wife was murdered and that he must reach the crime scene. But when he reached the crime scene, he was arrested by the sheriff.

How did the sheriff know that he was the culprit?

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