Can you solve the police puzzle from just one detail of the photo?

mporeite na lysete ayton ton grifo pararatirontas mia kai mono leptomereia 1 ΑΣΤΥΝΟΜΙΚΟΣ, ΓΡΙΦΟΣ, ΤΕΣΤ

Riddle: Do you think you are good at tests and puzzles? In case you want to test your strengths, you can see what is below. You are a police inspector and you have to solve the puzzle, which is below. In more detail:

mporeite na lysete ayton ton grifo pararatirontas mia kai mono leptomereia ΑΣΤΥΝΟΜΙΚΟΣ, ΓΡΙΦΟΣ, ΤΕΣΤ

Riddle: What the inspector said

An inspector was working during the holiday season when he was called to work on the morning of December 25th. He visited an apartment, rang the bell and a minute later a sleepy owner opened it. The inspector introduced himself and said: "I have to thoroughly inspect your apartment. Your neighbor mentioned that yesterday, Christmas Eve, he came to your house for a party. "And while he was singing with your family next to the Christmas tree, which was shining from the colorful lights that were flashing, you broke into his apartment and stole a large number of valuables."

Riddle: What the apartment owner answered

"This is not true! Our family celebrated Christmas Eve at our friends' house. We went to them in the afternoon. I just managed to decorate our Christmas tree before we left. We returned home long after midnight and immediately fell asleep. "If you want, I can wake up my wife and my son to confirm everything I told you." "There is no reason for that," the inspector interrupted. "It is clear to me that your neighbor is a liar."

The question

How did the inspector find out so quickly that the neighbor was a liar?

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