Convicted serial killer Tommy Lynn Sells, who was sent to prison in 1999 and claimed responsibility for dozens of murders across the country, was executed Thursday in Texas.
Sells, 49, was convicted of killing 13-year-old Katy Harris while she slept in her Del Rio, Texas, home. Her murder landed Sells on death row, but he has been linked to at least 17 other killings and claims he has killed as dozens more.
Sells declined to make final remarks before his death, then took a few breaths, closed his eyes and began to snore as the lethal-injection drugs took effect, The Associated Press reported. He soon stopped moving and was pronounced dead 13 minutes later at 6:27 p.m. CT.
Sells' execution earlier had been halted when a district court ruled that the Texas prison system was required to disclose information about its lethal-injection drugs supplier and how the drugs are tested. But a federal appeals court on Wednesday threw out the ruling and reversed the decision.
Sells' attorneys made a plea to the U.S. Supreme Court to stay the serial killer's execution, but their plea was rejected Thursday.
In a statement to ABC News Thursday, Sells' attorneys said, "It is our belief that how we choose to execute prisoners reflects on us as a society. Without transparency about lethal injections, particularly the source and purity of drugs to be used, it is impossible to ensure that executions are humane and constitutional. It is our hope that the U.S. Supreme Court and the Texas courts will ultimately agree that we must have transparency about the execution process in order to ensure that prisoners are able to protect their Eighth Amendment rights."
Sells was a subject in a 2010 special ABC News report entitled, "Nightline Prime: Secrets of Your Mind," which followed the inner workings of the human brain and its effects on behavior. He was included in a segment about researchers studying the brain scans of murderers and psychopaths in hopes of discovering why someone would turn into a vicious killer.
Sells, an extreme example of someone with a murderous mind, talked about his gruesome past with ABC News in a chilling 2010 jailhouse interview.
As a young boy growing up in St. Louis, Sells was addicted to killing by the time he was 14.
"I am hatred. When you look at me, you look at hate," Sells said in 2010. "I don't know what love is. Two words I don't like to use is 'love' and 'sorry,' because I'm about hate."
His drifter lifestyle helped him elude police for nearly 15 years as his victims turned up from coast to coast. Sells said his drug use fueled his killing sprees.
"The first time I did a shot of dope, it was the best feeling I ever had in my life. The first time I killed somebody, it was such a rush," Sells told ABC News at the time. "It was just like that, a shot of dope every time I did it, it was that rush again, and I started chasing that high."
During the interview, Sells appeared nonchalant when asked about the victims he had slain, and spoke very matter-of-factly when recounting his killing methods: beatings, stabbings, strangling. He even raped many of his targets before slicing their throats.
"I like to watch the eyes fade, the pupil fade. It's just like setting their soul free," Sells said at the time, without showing emotion. "I don't have an on-and-off switch. I'm just after that drug. I'm after that feeling."
One of the more horrific crimes Sells has confessed to committing was the slaying of 30-year-old Eileen Dardeen and her family.
Dardeen was seven-and-a-half months pregnant when Sells allegedly beat her to death. During the attack, she went into premature labor and gave birth to a baby girl.
Investigators determined the newborn was alive when she was born, but was later found bludgeoned to death, as was Dardeen's 3-year-old son.
Her husband's body turned up a few days later. He had been shot three times in the head.
Investigators involved with the Dardeen case said if Sells were not already sitting on death row in Texas, they would have arrested him for this crime.
Sells blamed his murderous rage on having an abusive childhood.
"I didn't want them to live through the pain I lived through," Sells told ABC News, explaining why some of his victims had been children.
Sells has left only one known survivor during his terrifying rampage.
Krystal Surles was just 10 years old when Sells tried to murder her while she was sleeping over at her friend Katy Harris' house in Del Rio, Texas.
Asleep on the top bunk, Surles awoke in the middle of the night to Sells killing her friend.
Though it happened years ago, Surles told ABC News in an interview that it was a night that will remain burned in her memory.
"He had a hand on her mouth and the knife on her neck, and she's looking at me, at the bunk bed," Surles told ABC News at the time. "He just cut her throat, and she fell to the ground."
Frozen with fear, Surles said Sells then walked towards the door, about to shut off the light, when he looked around the room one last time.
"That's the first time he noticed me," she said. "He ... didn't hesitate at all. I mean, just shut the door, came right back towards me with the knife."
"The only thing that he said is, 'Move your hands' ... and he reached over the top bunk and ... cut my neck."
Sells severed Surles' windpipe and grazed her ceratoid artery. She played dead on the floor in a pool of blood until she thought Sells had gone, then she ran for help at a neighbor's house.
Surles later identified Sells as her attacker and as the man who had brutally killed her friend, which finally put an end to his killing spree. He was later found guilty.
Sells told ABC News in 2010 that he still remembered the one that got away.
"There's not a day goes by that I don't think of her," he said at the time.
The Associated Press contributed to this report.