“It bothers me a great deal,” he says. “I know of hundreds of other cases that are not solved. But they’re not mine. It’s so damn frustrating.”

The Dermonds, both in their late 80s, were New Jersey natives who raised four children before moving to Georgia in the late 1980s, initially settling along the Chattahoochee River near Roswell.

For much of the 1990s in metro Atlanta, Russell Dermond, formerly an executive for a New York-area clock-making company, ran a chain of Hardee’s fast-food eateries.

Joe Kovac Jr.

Joe Kovac Jr.

In the late ‘90s, they retired to a $1 million house on Lake Oconee, 60 miles southeast of Stone Mountain’s peak, in a gated golfing enclave known as Great Waters.

The gruesome, mystifying nature of their killings has generated broad public interest. A slew of true-crime television shows and podcasts have featured the case. Sills, an orator and natural showman, has welcomed most of them. He has entertained their producers and their questions. Anything to conjure a tip.

Most days, though, his only audience consists of the piles of Dermond documents, including a near avalanche in a corner of his office.

It turns out that, sometimes, the thicker the file, the less you know.

VIDEO: An inside look at one of the labs that helped uncover new DNA evidence in Lake Oconee murder

‘Oh, my God’

The 911 caller was breathless, shocked by the grim scene she and her husband had discovered the morning of May 6, 2014.

“I think I have somebody dead,” the caller, 68, gasped.

“Who is it?” the emergency operator asked.

“The Dermonds,” the caller, a friend of theirs, said. “I just came to check on them. They’ve been missing for about four days. ... Oh, my God.”

“They’re both dead?” the operator asked.

The caller can be heard asking her 75-year-old husband, “Did you find both of them?”

He had not.

“No, it’s just one,” the caller said. “I don’t know where the other one is.”

The Dermonds’ friends who’d called 911 had gone to see about them that Tuesday morning after the Dermonds failed to show up at a Kentucky Derby viewing party the Saturday prior.

Sills was in his office when the alert came in, but in seconds he was out the door, speeding the 14 miles to Great Waters in his black Suburban. He almost beat the first patrolman there.

He had been the sheriff of his home county since 1996. There hadn’t been a double murder there since 1984. When he arrived at the Dermond place, the neighbors who’d called for help were in the driveway, distraught.

Inside, Russell Dermond, 88, was dead on the floor of his carport between a small Lexus SUV and a Lincoln Town Car. He had been decapitated. His wife of 68 years, Shirley, 87, was nowhere to be found.

There appeared to be no motive. There were no signs of robbery or burglary. Nothing in the house looked out of place aside from an end table lamp and a few towels removed from a bathroom.

Ten days would pass before a pair of fishermen found Shirley Dermond’s corpse in the lake, 5 miles from her house by boat. Her head was bashed open with a hammer-like implement, her ankles bound with a cord to a pair of concrete blocks.

The killings and the absence of an arrest have left the couple’s family bewildered.

“I’m to the point now where, yeah, sure, I’d love have this person pay for their crimes and hopefully not commit any more and all that,” says one of their sons, Keith Dermond, 65. “But really it’s more about just knowing what the heck happened. It eats at you.”

‘A tortuous affair’

As sheriff, Sills, 68, is also his department’s chief investigator.

He has a reputation as a bloodhound and a bulldog. He resembles the latter, stout and blunt, a history professor with a badge. His whitecap of a mustache crests over a mouth that can spout case law and the Old Testament in a learned drawl that somehow rings clear. Or as his voice might put it, “klee-uhh,” with perfect over-enunciation.

He may be the state’s most recognizable local lawman.

In 2017, he was at the center of the manhunt for a pair of inmates who murdered two corrections officers in a wild escape from a prison bus.

Twenty years ago, his racketeering and child molestation investigation into cult leader Dwight York landed York in the “Supermax” federal prison in Colorado with a 135-year sentence.

In all, six killers collared by him have been sent to death row.

The Dermond case, however, has haunted him for more than 3,600 days.

“It has been a tortuous affair, if nothing but an albatross for me,” Sills says from behind his desk, which is also overflowing with papers.

Joe Kovac Jr.

Joe Kovac Jr.

As it happens on this particular morning, an email has caught his attention. Sills, sporting a soft-blue Oxford shirt and a gold-striped maroon tie, swivels in his chair to face a computer.

Two months prior, in February, he had hand-delivered a trove of Dermond case evidence to a forensics laboratory in Utah for DNA testing. The lab can detect sub-microscopic wisps of genetic code left when someone casually touches an object.

“My Hail Mary pass,” Sills calls it. “It’s so far down the field, I can’t tell if the guy caught it.”

Peering at his computer screen, he clicks open the email. It’s from the Utah lab.

Attached are the DNA test results. He examines a page of notations with words like “deconvoluted” and spelled-out numbers, “septillion,” and phrases that mention “a variant of the sequence of nucleotides.”

He sighs and pores over a particularly indecipherable passage.

“What the (expletive),” he says, “is allelic activity?”

He turns to a visitor and apologizes.

“I’m sorry I’m so ignorant of this. But I am.”

Sills needs clarification. He dials the number to the lab. But it is barely 9 a.m. out West. No one answers.

The sheriff leaves a message. Then he waits.

‘There’s no mess’

Everyone seems to have a theory in the Dermond killings.

Could the culprit be someone the Dermonds knew? Possibly. Very little in their house was out of place. There was no forced entry. They had no security cameras, and one at the entrance to their subdivision had been zapped useless by a thunderstorm weeks earlier.

Their bed was unmade, but otherwise the place was spotless.

“Drug-crazed, random killers — whether they’re the Manson family or just Beebop down the street that’s done gone crazy on meth — they leave a mess. There’s no mess here,” the sheriff says. “We sprayed every inch of the house with luminol.” That’s a chemical used to detect cleaned-up blood.

It was almost as if the killings happened elsewhere.

“That’s exactly what I think,” Sills says.

But where? On a boat? A neighboring house? The sheriff hasn’t a clue.

Sills has interviewed all of the Dermond children, two sons and a daughter. None is a suspect. A third son, Mark Dermond, was shot to death in 2000 during a crack cocaine deal in downtown Atlanta. His killer is serving a life sentence for murder. Sills doesn’t believe anyone connected to that crime had a role in the lake slayings.

Might the attacker have been a hitman? Maybe, but the savagery hints to a deeper emotional involvement.

Russell Dermond’s cause of death is unknown. It is possible he was shot in the head. But his head was severed. It has never been recovered. Sills figures the decapitation was to remove some physical evidence on his head, or a bullet inside it, that investigators might tie to a suspect. “I’ve never thought it was any other reason,” he says.

The illogical neatness in how Russell Dermond’s corpse was left — placed just so on a pristine garage floor, save for a puddle of blood — puzzles Sills. Maybe the killer intended to haul it to the lake as well.

“I’m not sure they weren’t coming back,” Sills says. “There are so many nuances, so many contradictions in this case. One, whoever killed (Shirley Dermond) thought she would never be found. That was their intent. So we would always be working an abduction. … Obviously, that person was not a professional assassin or she would never have been found.

“The problem with this case is there’s no theory so far that fits,” Sills says. “All these people say it had to be a professional. Well, it wasn’t.”

‘Somebody knows’

The sheriff’s desk phone rings after lunch.

It’s the lab in Utah.

Sills tells the analyst that he needs a layman’s explanation of what, precisely, has been found.

The analyst says a mix of DNA has been discovered. Then she meanders through a technical summation that borders on quantum chemistry. But the analyst is just being methodical, going down a list of data, interpreting as best she can.

Sills, impatient, shifts in his chair.

The analyst finally discusses a piece of Russell Dermond’s clothing. In that moment, Sills has high hopes that whoever killed him may have touched the attire and left a trace of DNA.

The analyst confirms that the clothing, not unexpectedly, does contain Russell Dermond’s DNA.

Then she says something that Sills almost cannot believe, that the clothing also contains DNA from an unknown individual.

“Is somebody else’s there?” Sills asks, making sure.

“Yes.”

Joe Kovac Jr.

Joe Kovac Jr.

When word of the discovery hits the news a few days later, Sills tells reporters it’s the best shred of a clue he has divined in 10 years. He cautions that more testing is needed for the mystery DNA to meet standards for entry in a national database, a step that could lead to a suspect. What he does not say is that he knows such a prospect remains a long shot.

He expects news coverage spurred by the 10th anniversary of the killings will generate tips. He’s dismissive of the idea that they might produce useful leads.

“None of them will be anything,” he says. “Now I hope there’s gonna be one that is. If hope springs eternal, I’m a friggin’ eternalist.”

It pains him that the killer he seeks has eluded him.

“It’s been 10 years. God knows what this person or persons may have done since,” he says.

He is asked what message he might send to the killer.

Sills replies instead with a proposition.

“Somebody knows who did this,” he says. “Whoever did this has done bad things before and will do bad things again. We’ve got reward money. If you want some money, I’ll give you some money. Whoever did this, they may be your best friend. But if they did this, they’ll cut your head off too.”