Brooklyn boy Leiby Kletzky's killer Levi Aron is every parent's worst nightmare (PHOTOS)

A missing person sign for Leiby Kletzky ,8, is seen posted in the Orthodox Jewish section of Borough Park in the Brooklyn borough of New York Reuters

Leiby Kletzky, the 8-year-old missing Brooklyn boy, was found brutally killed and dismembered on Wednesday morning. His chopped-up remains were found in the murderer's refrigerator and a nearby dumper. The murderer has already pleaded guilty of killing.

Kletzky disappeared on Monday, when he was on the way to his parents' home from a summer camp. This is the first time Kletzky was coming home alone with his parents' agreement.

Start the slideshow to find out how the investigators found the killer.

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