CBS NEWS "48 HOURS MYSTERY" -- SATURDAY, APRIL 14

A YOUNG COUPLE IS GUNNED DOWN IN A BUSY INTERSECTION AND THE MAN WHO PULLED THE TRIGGER IS CAPTURED, BUT NOT PUT ON TRIAL WHILE POLICE SEARCH FOR THE MAN WHO "PULLED THE STRINGS"

"48 HOURS MYSTERY" -- SATURDAY, APRIL 14

Newlyweds Heather and John Grossman were driving to lunch 10 years ago on a sunny Florida day when bullets suddenly pierced their vehicle. John survived the shooting but a bullet ripped a fist-sized hole in Heather's neck, severing her spinal cord leaving her a quadriplegic. Investigators found the shooter, Roger Runyon, who detailed how he used a long rifle to fire at the Grossmans. But investigators also uncovered three other men who allegedly conspired with Runyon. Yet investigators soon realized that the case against the group was missing one big piece -- the puppet master -- the person investigators believed to be responsible for planning the crime. Correspondent Troy Roberts reports on this bizarre conspiracy. 48 HOURS MYSTERY: "The Puppet Master" will be broadcast Saturday, April 14 (10:00 --11:00 PM, ET/PT) on the CBS Television Network.

Who commissioned this crime and what did he have to gain? And just how connected was the criminal mastermind to Heather all along?

48 HOURS MYSTERY: "The Puppet Master" was produced by Peter Henderson and Charlotte Fuller. The senior producer is Anthony Batson, the executive editor is Al Briganti and the executive producer is Susan Zirinsky.

Editors' Note: To read more about this case, including Troy Roberts' behind-the-scenes reporter's notebook, and see exclusive 48 HOURS MYSTERY video, visit http://www.cbsnews.com/. CBS News 48 HOURS MYSTERY broadcasts are now available on iTunes.com.