Floyd and Vera Hill led a tranquil life in rural Alabama. Married for 55 years, they were devoted to each other, with the sprightly 87-year-old Floyd acting as caretaker for 72-year-old Vera, who was diabetic and in poor health.

To earn some cash and keep themselves busy, the couple held the occasional yard sale and enjoyed spending time with their grandchildren.

All that changed one terrible June day in 2004, when the Hills were bludgeoned to death at their home in Guin, a small city about 70 miles northwest of Birmingham.

Now 20 years later, the man convicted of murdering them is about to be executed. USA TODAY is looking back at the tragic crime, who the Hills were and why they were killed.

What happened to Floyd and Vera Hill?

Given their age, the Hills' adult grandchildren were in the habit of checking in on them. So their daughter, Brenda Barger, and granddaughter Angela Freeman Jones were worried when they couldn't reach the couple on June 24, 2004, court documents describe.

The couple wasn't answering their phone or their front door, so the women called police.

Guin police officer Larry Webb arrived at the Hills' home shortly after dark. When his knocks and calls also went unanswered, he inspected the property, noticing that Vera Hill's bed was still made, her walker was in the living room, and that Floyd Hill's alarm was going off.

Webb made his way toward the couple's padlocked shed and stood on a bench to get a look inside. What he saw was horrific.

The couple was lying in pools of blood and had terrible injuries to their heads and faces. Amazingly, he saw Vera Hill's arm move ever so slightly.

Webb broke into the shed, and found that Vera Hill was still breathing but that her husband was dead.

“Let me out of here,” Vera Hill managed to say.

Vera Hill survives attack, but dies months later

Although Vera Hill initially survived the brutal attack, she died more than two months later from complications from her injuries on Sept. 12, 2004. She was surrounded by loved ones.

“The head injuries Vera Hill received were life-threatening and ... Vera Hill would have died within hours of receiving the injuries if she had not received the type of medical attention she did,” according to testimony from Sherry Melton, a trauma surgeon at University of Alabama Hospital. 

Both Floyd's and Vera's cause of death was listed as blunt- and sharp-force trauma to the head and neck.

In the last months of her life, court records say, Vera Hill struggled mightily and the only word she could say was Floyd.

Jamie Ray Mills convicted of killing Floyd and Vera Hill

Jamie Ray Mills, who was 30 at the time of the crime, was convicted of the couple's murder, largely based on testimony from his wife, JoAnn Mills.

The Mills spent the night before the killings smoking meth and went to the Hills' home asking to use their phone, court records show. The Hills obliged and even began showing the couple their yard sale items when JoAnn Mills says her husband attacked and killed them with a machete, tire tool and ballpeen hammer, court records show.

Prosecutors say the motive was robbery and that the Mills made off with $140 and some prescription pills. Mills, who is now 50 and maintains his innocence, is set to be executed on Thursday by lethal injection.

His trial attorney, John Wiley, argued to jurors that Mills didn't deserve the death penalty for a number of reasons, among them his two then-teenage sons.

"By being alive and actually being a dad to them, even if it’s a long-distance dad, he can maybe show them where he went wrong and keep them from going down the same path," Wiley said.

Jack Bostick, the district attorney who argued for the death penalty against Mills, told jurors that "what happened to Floyd and Vera Hill was wrong, immoral and barbaric."

"You have got two elderly people, retired, having a yard sale, had it going on for about a week. … somebody comes by under the guise of using their phone and sits there and keeps acting like he’s making phone calls, getting the courage up," Bostick said. "It's almost beyond imagination that anyone could be that cruel to another human being, to have that done to them."

He added: "The Hills didn't have a chance."

Contributing: Amanda Lee Myers