Preview: "48 Hours" double feature

It's double the mystery Saturday, Aug. 22 starting at 9/8c on CBS: Who wanted a one-time millionaire dead more: his ex-wife or his son? Peter Van Sant investigates. Then at 10/9c: Can a Facebook-savvy investigator solve the case of a mom murdered two decades ago? Troy Roberts investigates. | DVR ALERT: "48 Hours" to air late, overnight in some cities