A Florida teenager was charged Wednesday with murdering his grandmother by stabbing her 93 times and shooting her in the head with a crossbow. Jasper Aristotle Smiddie, 19, allegedly stabbed his grandmother, 67-year-old Gloria Helfrich, 93 times, hitting her with a wrench and then shooting her with a crossbow. Authorities say Smiddie decided to kill his grandmother to make his uncle suffer. They say he originally plotted to kill his uncle, but decided to kill Helfrich instead. \"He decided, \'Well, I\'ll kill my grandmother instead so that my uncle has to live with the death of his mother for the rest of his life,\' \" Sheriff Grady Judd of the Polk County Sheriff\'s Department said. Authorities say they do not know why the teen hated his uncle so vehemently. Police say Smiddie killed his grandmother in her bedroom in the home they shared. Then, in a bizarre twist. he locked the door and waited for his uncle to get home. The teen then ate dinner and watched television with his uncle, who had no idea his mother lay dead in her bedroom. Smiddie left the home in the morning, then reportedly called his father in Tampa and told him what he had done. His father called the police, and directed them to the woman\'s body. Smiddie was arrested near his girlfriend\'s home and charged with first-degree murder.(Fox news)