In the summer of 2013, Minnesota resident Gary Herbst seemingly vanished. But before anyone realized he was missing, neighbors noticed something strange: late one night, they watched a rolled-up carpet being carried out of his home. Years later, investigators would uncover a startling discovery that revealed what really happened. In an exclusive interview, 48 HOURS correspondent Peter Van Sant speaks with Gary Herbst's son, Austin Herbst, about why he killed his father. 

What begins as a burglary investigation quickly turns into something far more sinister. When a thief is caught in the act, he sends police down a trail of evidence that reveals the murder of Harold Allen, involving thousands of text messages, unusual poisons and a root beer float. How did a sweet treat become central to a deadly crime? 48 HOURS correspondent Peter Van Sant reports in "The Root Beer Float Murder."