The unsolved beheading of a retiree and the killing of his elderly wife has so rattled their gated, lakeside Georgia community that neighbors are casting about for even outlandish explanations. Was it a mob hit? A drug dealer? A hungry alligator?

The peaceful neighborhood where the couple was found dead hadn't seen as much as a burglary in recent memory.

Then, in early May, concerned friends found the headless body of Russell Dermond, 88, in the garage of his home on Lake Oconee. Shirley Dermond, 87, was originally thought to have been abducted until her body was found a few weeks later in the lake. Russell Dermond's head has still not been found.

Even though law enforcement thinks the Dermonds likely knew the person or people who attacked them, their advanced age, the beheading after he was killed, and the fact that it all happened in a seemingly secure community that has a manned guardhouse has left neighbors rattled, according to Putnam County Sheriff Howard Sills.

"It is the prime topic of conversation around," said Ron Bridgeman, senior editor of The Eatonton Messenger, a weekly newspaper. "It has consumed hours and hours and hours of our time."

Despite interviewing hundreds of people and looking through reams of records, Sills has been frustrated by the lack of obvious motive and is hoping for a breakthrough. And for the first time in his 18 years as sheriff and four decades in law enforcement, he's asked the public to donate to a reward fund.

He believes someone knows something and while they may not feel compelled by a sense of what's right and wrong, he said: "I've found that almost all of them will respond to enough money, and we intend to offer enough money out there to spark that mercenary side of somebody."

Sills says he can't even remember so much as a burglary in the Dermonds' community during his tenure as sheriff. The surrounding county sees occasional domestic violence or drug-related killings but the last time there was a "whodunit" murder, where they didn't immediately know who the killer was, was about five years ago, when a body was found beaten beyond recognition with no identification, Sills said. But they made arrests in that case within a week.

In quiet downtown Eatonton, about a dozen miles from the gated community of Great Waters where the Dermonds lived, antique shops, clothing boutiques and restaurants fill historic store fronts that have plaques outside saying what the building was originally -- cotton warehouse, bank, grocery, barber shop. And people there are talking about the mystery, said Karen Bridgeman, Ron Bridgeman's wife and the newspaper's managing editor. "There are as many different theories as there are people in the county."

Some of the most common are that the Dermonds, originally from New Jersey, had organized crime ties and were victims of a mob hit or that their deaths are related to the killing of their oldest son in 2000 in a drug deal gone bad. The craziest tip authorities got was that it was likely a female alligator seeking food for her young, the sheriff said.

Sills is tired of all the theories and speculation. He has investigated the Dermonds' lives in depth and has determined that they worked hard, paid their taxes, went to church. There's no indication of any illegal activity or association with unsavory characters, he said. There's no indication that anything was taken from the home.

He simply can't figure out who would want the Dermonds dead.

Russell Dermond had a corporate job and moved around until finally ending up in the Atlanta area. After he retired, he got into the fast food business, buying a number of chain restaurants. When he retired for a second time, he and his wife moved south to Lake Oconee. He played golf regularly until a few years ago and still liked to take walks, the sheriff said.

Shirley Dermond was an avid bridge player, rarely missing the twice-weekly meetings of her club.

They lived a remarkably simple life, Sills said. Russell Dermond only had two credit cards and put everything on those to rack up rewards points. He didn't even have an ATM card as he never carried cash, the sheriff said.

They were regulars at the Lake Oconee Community Church, missing services only when they went to visit their children in other states, Pastor David Key said. They were social and clearly had money but didn't flaunt it, he said.

"They were just a nice, unassuming couple," Key said.

The Dermonds had three sons and a daughter. Their oldest son had a serious drug problem and was shot to death while trying to buy drugs in a rough neighborhood in Atlanta in 2000, Sills said.

The Dermonds' oldest living son, Keith, did not return calls from The Associated Press seeking comment. The other two children could not be reached. But Sills said he's questioned all three at length and talks to at least one of them almost every day. They've been extremely cooperative, answering his inquiries quickly and getting him any information he needs, Sills said.

Sills believes the Dermonds likely were at least acquainted with the person or people who killed them because there was no sign of forced entry and no sign of a struggle. While he's not positive the killer or killers arrived and left by boat to reach the secluded cove where the couple's home sits, he's certain a boat was used to dispose of Shirley Dermond's body, which was found in the lake about five and a half miles from their home.

As he puts the pieces together slowly and hopes for some sort of a break, Sills said he remains undaunted.

"They've done a good job concealing themselves," he said of the killers. "We've got to do a better job of finding them."