A Knoxville, Tennessee, man was executed by lethal injection on Thursday after being convicted for the rape and murder of a 7-year-old girl 32 year ago.

According to witnesses, his last words were, "I just want to say I'm really sorry, and that's it." He was convicted in 1986 for the death and rape of Paula Dyer a year prior. He was babysitting Paula when the incident happened.

Born in 1958, Irick had a troubled upbringing. He showed signs of mental illness at the age of six, WBIR reported.

He was evaluated by a clinical social worker Nina Braswell Lunn. She described him as “disruptive boy.” He told her stories about being tied up and beaten up at home as his parents couldn’t control him. Lunn also testified that Irick might have suffered from mild organic brain damage.

Due to his problems, Irick was institutionalized for a year and then later sent to an orphanage that provided care for emotionally-disturbed children in Sevier County. In 1972, during a visit to his parent’s home, he destroyed their television set with an ax, wrecked the flower beds, and even shredded his younger sister’s pajamas using a razor blade.

When Irick was in his 20s, he was working as a dishwasher at Dixie Plaza Truck Stop on Lovell Road. This is where he met Paula’s parents, Kenny and Kathy Jeffers, for the first time.

"Kenny worked as a diesel mechanic and I waited tables at Hagamans Truck Stop. Kenny met Billy first, then we got to be friends and he moved in with us at our house in Clinton," Kathy said.

The pair had five children in total, some from previous relationships. "All of the kids were really close and loved each other. There was no 'step' or 'half' brother or sister. They were brothers and sisters from the start. They would seriously fight anyone who told them they were not full brothers and sisters and still feel that way," Kathy said.

Irick soon became extremely close with the family. The children used to call him “Uncle Bill.” He used to take care of the kids when the couple had nightshifts.

Irick even saved the lives of two of the boys in 1985, when the Jeffers house caught on fire. The family, along with Irick, moved into a rental house on Exeter Avenue in Knoxville's Beaumont community soon after.

Kenny and Irick had a fall out a few weeks prior, but Kathy called him back to babysit when they had nightshifts one day.

“I don’t know if you call it ‘intuition,’ but something seemed off about him. I stopped at a payphone and called Kenny at the truck stop and asked him to get back to the house,” she told WBIR.

Before they could go check up, they received a call from Irick at work. "It's Paula. I can't wake her up," Irick said.

Kenny reached home to find a half-nude Paula lying on the bed. There was a puddle of blood between her legs. She was pronounced dead at the hospital.

Autopsy revealed that Paula had been brutally raped. She had died due to asphyxiation.

Irick was found a day later by the police at Baxter Avenue near the Interstate 275 entrance ramp. He was trying to hitchhike.

Soon after arrest, Irick confessed his crimes. In November 1986, he was sentenced to death.

But due to repeated appeals and contention of the death penalty, his execution was postponed for over 30 years.

The U.S. Supreme Court Justice Elena Kagan denied Irick's last appeal for a stay of execution on Thursday afternoon. Irick was injected with a three-drug lethal injection at 7 p.m. CST (8 p.m. EDT).

Witnesses say immediately after, he closed his eyes and began snoring. He was pronounced dead at 7.48 p.m. (8.48 p.m. EDT).