Elizabeth Vargas

It was just after eight when the Whitaker family leaves the restaurant and Bart's secret murder plot is unfolding as he expects, just as he and his unwitting family arrive home. The Whitaker family suspects nothing, but as they enter the house, Bart hangs back.

It was just after eight when the Whitaker family leaves the restaurant and Bart's secret murder plot is unfolding as he expects, just as he and his unwitting family arrive home. The Whitaker family suspects nothing, but as they enter the house, Bart hangs back.

As shots ring out, a neighbor calls 911.

As shots ring out, a neighbor calls 911.

First on the scene, Sugarland police officer Phil Prevost finds 19-year-old Kevin Whitaker dead where he fell, a single bullet in his chest. Trisha Whitaker also dies of a single gunshot wound soon after she's airlifted to the hospital. Incredibly, Kent Whitaker survives the attack shot in the chest. Also wounded, Bart makes for a convincing fourth victim.

First on the scene, Sugarland police officer Phil Prevost finds 19-year-old Kevin Whitaker dead where he fell, a single bullet in his chest. Trisha Whitaker also dies of a single gunshot wound soon after she's airlifted to the hospital. Incredibly, Kent Whitaker survives the attack shot in the chest. Also wounded, Bart makes for a convincing fourth victim.

And it works like a charm.

And it works like a charm.

Homicide Sergeant Marshall Slott thinks he's looking for a burglar with bad timing.

Homicide Sergeant Marshall Slott thinks he's looking for a burglar with bad timing.

The dogs pick up a scent in the house and follow it outside to a dead end. Sergeant Slott scans the crime scene for anything that might lead him to the killer. He finds drawers pulled open as if by a burglar, a gun safe pried open, four spent shell casings and on the kitchen floor, a nine millimeter handgun with four bullets missing from its clip.

The dogs pick up a scent in the house and follow it outside to a dead end. Sergeant Slott scans the crime scene for anything that might lead him to the killer. He finds drawers pulled open as if by a burglar, a gun safe pried open, four spent shell casings and on the kitchen floor, a nine millimeter handgun with four bullets missing from its clip.

Investigators find no suspect fingerprints at the scene. They take the gun back to the crime lab for a closer look.

Investigators find no suspect fingerprints at the scene. They take the gun back to the crime lab for a closer look.

Investigator Max Hunter carefully tests the weapon and makes a hopeful discovery.

Investigator Max Hunter carefully tests the weapon and makes a hopeful discovery.

Tracking dogs identify the shooter's scent on the gun, but DNA analysis comes back negative. It seems the killer made a clean getaway.

Tracking dogs identify the shooter's scent on the gun, but DNA analysis comes back negative. It seems the killer made a clean getaway.

Back to square one, Sergeant Slott and his partner, Detective Billy Baugh, go to the hospital to interview the survivors, Kent and Bart Whitaker.

Back to square one, Sergeant Slott and his partner, Detective Billy Baugh, go to the hospital to interview the survivors, Kent and Bart Whitaker.