Sherry Schweder worried about the group of mixed-breed dogs she saw wandering near her home that authorities say mauled her and her husband to death along a rural stretch of road in northeast Georgia. The 65-year-old animal lover was taking an evening stroll when she was attacked by the pack of wild dogs, authorities believe. Her husband, Lothar Schweder, a retired professor, had gone out in search of her. A shredded piece of shirt, some strands of hair and bloodstained dirt were all that remained Tuesday where the couple was killed. Paramedics who came to the grisly scene Saturday morning found the suspected attackers standing guard. While it's unclear exactly what happened because there were no witnesses, officials have rounded up 16 dogs they believe were involved. Schweder had told one of her sons that no one seemed to be caring for the dogs, said Jim Fullington, special agent for the Georgia Bureau of Investigation. Experts say the attack is extremely rare - so rare "you are more likely to be killed by a bolt of lightning than by a dog," said Adam Goldfarb, a spokesman for the Humane Society of the United States. The feral dogs didn't belong to anyone, but a man who owns a house at the end of the road had been feeding them, said Oglethorpe County sheriff's Capt. Shalon Huff. The man told authorities the dogs never behaved aggressively toward him, and he did not believe the dogs had killed the couple. "Sometimes the pack mentality can play a role. One dog gets aroused and that revs up his buddies," Goldfarb said. The dogs were aggressive toward authorities who rounded them up using traps and tranquilizers, Huff said. At one point, a group of them cornered two people against a vehicle. There were no signs the dogs were rabid, Huff said. Authorities believe Sherry Schweder went for an evening walk near her home on Friday, perhaps looking for one of her own dogs that had been missing for about a month. At some point, Schweder was attacked. Preliminary autopsy results showed she died from animal bites. Authorities believe Lothar Schweder, 77, later went looking for her in his car and came across his wife's body. There were signs of a scuffle, several shoe prints and what appeared to be paw prints in the mud, authorities said. He may have tried to pull out his cell phone before he succumbed to the attack, Madison County Coroner James Mathews said. Autopsy results show Lothar Schweder also died of injuries from multiple animal bites. A group of Jehovah's Witnesses walking in the same area discovered the bodies Saturday morning and called police. Four days later, a faint unpleasant smell still hung in the air. There have been at least 20 deadly dog attacks in the U.S. this year, 22 in 2008 and 33 in 2007, said the Humane Society's Goldfarb, compared with about 75 million owned dogs. The National Weather Service says there were 27 lightning deaths so far this year, 28 in 2008 and 45 in 2007. Dogs that attack also typically are not spayed or neutered, which can contribute to aggression, Goldfarb said. The dogs in the attack are not believed to have been sterilized. With a voice that wavered at times, one of the couple's sons, Mark Schweder, described his parents as "kind people who lived a simple life out here." He said his parents had divorced and his father moved to Kansas, where the elder Schweder ran the library and worked in public relations for a state penitentiary. But after retiring in 2001, Lothar Schweder moved back to Athens to woo his ex-wife back. "They always loved each other. My dad pursued, pursued and finally scored again," his son said with a smile. His mother worked as a bibliographer at the University of Georgia's library. In the early 1970s, his father was a German and philosophy professor at the school, the son said. Mark Schweder, who lives in Aiken, S.C., said his parents, especially his mother, were animal lovers. He also said he did not want charges to be brought against the man who fed the dogs. "It's just a horrible accident," Mark Schweder said. By Tuesday evening, 11 dogs and 5 puppies had been taken to the Madison-Oglethorpe animal shelter, where the staff was beginning court-ordered euthanizations. Authorities were still trying to catch two other dogs seen in the area. Meanwhile, the shelter has been asked to look for homes for the Schweders' 20 cats and seven dogs.