The Mirror Mystery ~Justin

It was a Friday and I was about to close up the store when I heard a scream coming from one of the the rooms behind me. Swinging the the heavy metal door back open I ran down the halls peering inside the rooms as I ran by until I found Sara in the third room from the door sitting in the corner of the room shaking, looking blankly into the half- opened closet in front of her. I walked to the closet and opened the door just enough so that I could see in, but the lights in the room were too dim to see anything so I pulled the string on the closet light . With a small click the light spread throughout the closet . Then I looked up to find Bill hanging to the wall with carpenters' knives through his hands holding him up and his throat cut from ear to ear. Then through the mirror on the closet door I saw a man with a hammer and a carpenter's knife still dripping with blood. I ran out the back door across the hall and into his car but I managed to get his license plate number through the reflection in the mirror 81811 but the state was covered by a piece of broken metal. When the man was out of sight I quickly called the police; they were here within minutes . I told them my story and they told me that they had just arrested a man with the plate number 81811 for overdue parking tickets just a few minutes ago.

The next day I had to go down to the station to identify the man in the mirror. The policeman said that they had the wrong guy and that after the man paid his fee and signed a few papers he was let go. The policeman had found the real murderer this morning trying to flee the city with illegal weapons in the trunk and the murder weapon under the seat. I still didn't know how the man knew...

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Answer: 

The police officer told me that the number I had seen in the mirror was reversed by the reflection in the mirror and instead of 81811 it was really 11818.