What is the Serial Killer Gene?

The serial killer gene has upended the longstanding debate of Nature vs. Nurture. Genetics provide an individual with a spectrum and his/her environment determines where s/he will lie within that spectrum. But what if a child was born with the serial killer gene? Could they fight their predisposition?

Waldroup Case

On October 13, 2006, Davis Bradley Waldroup, Jr. drank heavily in his trailer on Kimsey Mountain in Southeastern Tennessee, his gaze shifting between the window and the .22 hunting rifle by the door.

Miles away, his estranged wife Penny urged a neighbor to call the police if she didn’t return by 7:30 p.m. She also asked her friend Leslie Bradshaw to take the ride. Ever since she and Davis separated, he made her nervous.

When Penny arrived that night, Davis stalked around the side of the trailer with the rifle gripped in his hand. All four children leaped out of the van, running in and out of the trailer as Penny and Leslie unloaded the kids’ sleepover bags and groceries they’d picked up on the way.

After unloading the van, Penny slipped behind the wheel, but Leslie hadn’t gotten back in the van. She was still standing outside the passenger door.

Davis claimed, “We need to talk.”

“I need to get to work,” said Penny. “We’ll talk when I return to pick up the kids.”

He snatched the keys out of the ignition and whipped the whole keychain into the woods. Penny begged him to let her and Leslie leave.

Rage rolled over his face. In his mind, Leslie was the main reason their marriage had fallen apart. Davis raised the rifle. Fired. Penny dove behind the passenger seat, crawling out the rear, sliding door. Leslie lay on the ground. Hovering above her, she pleaded with Leslie to wake up. “We need to escape!”

Leslie didn’t respond.

As Penny lingered over her dead friend, trying to grasp their grave predicament, Davis stormed around the back of the van. Penny sprinted up the side of Kimsey Mountain. A gunshot rang out. Her husband shot her in the back. While struggling to her feet, Davis caught up and shoved her back to the ground. Lying on her back, Davis aimed the rifle at her head. Penny kicked the barrel and the rifle slid down the side of the mountain.

Nothing would deter Davis.

He drew a pocketknife and slashed at her forearms as she tried to protect her face. The couple struggled on the ground, and Penny finally managed to pry the knife out of his hands. With all her might, she threw the pocketknife as far as she could, then leaped to her feet and sprinted toward the nearest neighbor, who lived a quarter-mile away.

Davis would never allow her to reach her destination. He raced to the trailer for more weapons. When he caught her again, he beat her in the head with a square shovel, all the while dragging her back to the trailer.

As they neared, the family dog growled at Davis, diverting his attention long enough for Penny to careen around the side of the trailer. But Davis was right on her heels. Scorching pain seared the back of her head as Davis swung the machete, chopping at her scalp again and again. Penny held up her arms to ward off the attack, but he wouldn’t stop. In fact, he sliced the pinkie finger off her left hand.

When Davis lowered the machete, he grabbed a fistful of Penny’s hair and dragged her back to the van, shoving her to the ground next to her dead friend. Then he kicked Leslie. When that didn’t satisfy him, he chopped her lifeless body with the machete.

Once he’d released some anger, he focused back on Penny, jerked her to her feet, and shoved her inside the trailer.

Battered, shot, and bloodied, Penny could barely stand on her own. Weak from blood loss,  she asked one of her daughters to bring her a glass of water and a towel. The daughter returned with a sheet, which she wound around her mother’s shredded arms.

Davis had other plans. “Tell your mother goodbye,” he said to the kids. “This is the last time you’ll see her.”

A teary-eyed Penny hugged each child, crying, professing her undying love. What else could she do? She’d fought long and hard—more than most could withstand—but it was no use. Her husband wouldn’t quit till he killed her.

Davis dragged Penny into the bedroom. “You’re too messy to have sex with. Take a shower.”

Penny refused. She didn’t want to make it easy for him to clean up her blood. With more pressure from Davis, she relented and washed up at the sink. When she stumbled back into the bedroom, Davis ripped off her shirt and tossed her on to the bed. He’d just climbed on top of her when their daughter yelled into the bedroom.

“There’s headlights in the driveway.”

Sexually frustrated, Davis stormed into the living room and separated the blinds on the window. A cop car idled outside.

With his back turned, Penny snuck out the front door and dove into the back of the cruiser. When the officer saw her condition, he threw the car in reverse to rush her to the hospital.

No, Penny begged, please don’t leave. My children are in the house. You need to protect them.

The officer secured Penny in the cruiser before approaching Davis Bradley Waldroup Jr., who stood outside the trailer, glowering at his estranged wife. When questioned, Davis freely admitted to attacking his wife and murdering her best friend. He even escorted the officer to Leslie Bradshaw’s body on the other side of the van.

Paramedics airlifted Penny to Erlanger Medical Center, where she spent a minimum of two weeks recovering from extensive, life-threatening injuries.

Two years later, August 2008, the Polk County Grand Jury indicted Davis Bradley Waldroup Jr. for two counts “especially aggravated” kidnapping, one count of 1^st degree murder, and one count of attempted 1^st degree murder. At trial, the jury returned a guilty verdict for aggravated kidnapping, especially aggravated kidnapping, voluntary manslaughter, and attempted 2^nd degree murder.

The court held sentencing till May 7, 2009.

The defense argued lack of evidence to support the charge of kidnapping against Leslie Bradshaw, citing the jury’s wording as proof.

[Defendant] did while armed with rifle, remove the keys from the ignition of the vehicle of Penny Waldroup in which Leslie Bradshaw was a passenger. That act interfered with the substantial liberty of Leslie Bradshaw. [Defendant] at that time inflicted bodily injuries which resulted in the death of Leslie Bradshaw.

The defense also argued the State did not present proof to the jury that his taking of the van keys “removed or confined” the victim, that she “was moving freely smoking a cigarette while Davis and Penny Waldroup argued . . .”

With the threat of a death sentence hanging over his head, Davis told the judge, “I snapped. I’m not proud of none of it.”

To spare his life, Davis’s legal team took an unusual approach, never before admitted in a capital murder case. They sent a sample of Davis Bradley Waldroup Jr.’s blood to the molecular genetics lab at Vanderbilt University in Nashville. Sure enough, they found a genetic variant on Davis’s X chromosome, one that coded the enzyme monoamine oxidase-A — otherwise known as MAOA, the warrior gene.

What is MAOA?

MAOA plays a key role in the breakdown of neurotransmitters, such as serotonin, dopamine, and norepinephrine. The serotonin system involves impulse control, affect regulation, sleep, and appetite. It’s a hormone that impacts our entire system. Serotonin also enables brain cells (and other nervous system cells) to communicate with each other. Dopamine controls our mood, motivation and reward, arousal, and other behaviors. The epinephrine/norepinephrine system facilitates fight-or-flight reactions and autonomic nervous system activity.

If left unchecked, these potent chemicals can build up in the brain and cause a lack of impulse control while increasing a person’s violence and rage.

In the Waldroup case, the defense claimed Davis’s genes turned him into a murderous sociopath. Thus, he should not die. On May 7, 2009, the court sentenced him to 32 years.

The Serial Killer Gene

Slapping a warning label on a genetic profile is a slippery slope, if you ask me.

Where do we draw the line? Do we institutionalize a child because they’re born with the serial killer gene?

It’s important to note that just because someone’s blood may show genes associated with violence, aggression, and impulsivity doesn’t mean they’ll become a serial killer. Nonetheless, I do find it fascinating.

COMT, SCL6A4, and DRD4 are other genes that fall into the violent category, but MAOA is the top contender for the serial killer gene.

What do you think? If a criminal has the serial killer gene, should s/he receive a lighter sentence?