He had previously committed half - a-dozen sex - murders .
Serial killer Edmund Kemper beat his mother to death in 1973 , along with one of his mother 's friends before turning himself in to the police .
Edmund Kemper had previously committed half - a-dozen sex - murders .
Serial killer Edmund Kemper beat his mother to death in 1973 , along with one of his mother 's friends before turning himself in to the police .