20 years after Scott Peterson was found guilty of the brutal slayings of his wife and unborn child, the convicted murderer will tell his side of the story. In a three-part tell-all docuseries set to air on Peacock on August 20, Scott, 51, will discuss the killings in a way that may even make viewers rethink their opinions on his guilt. “What he will have to say will shock everyone,” a source spilled to a news outlet. “He talks to the series director [Shareen Anderson], who has been investigating the murder case for over a decade.” “The interview will be chilling,” added the source. “People may…