He didn't know anything about his father's lost cousin but recognized that the lake was in the town where his father grew up and sent him the article.
"I thought, Oh, my gosh. I looked at the 50s Chevy that was there and I thought, you know, he left in a Chevy. I just kind of put two and two together and that was my first inkling that it was him."
Hammack got in touch with local authorities and said everything he told them matched up to what they knew. A DNA test has yet to be done to confirm that the remains are those of Clebern Hammack.
He was last seen in 1969 when he was leaving a fill-in job at a restaurant where Cletius Hammack's mother also worked. On the day he disappeared, they both left the restaurant at the same time.
"She got in her car. He got in a car with a man and a woman and that was the last anyone ever saw of him," Hammack said of his cousin. "He just vanished. That was it."
The family had no idea what happened. They knew that Clebern had received his paycheck that day and there were rumors that maybe someone hit him over the head and dumped his body. The rumor was that he was in Foss Lake.
"It was extremely hard on his mother and up to the day she died, she was about 100 and she really thought he was coming back and that he was alive," Cletius Hammack said. "She's the one that never got over it."
She died in the 1990s, still thinking that her son was alive.
Both families are now coming to terms with the discoveries and grateful for the closure.
"It's a happy day for all of us," McManamon said of her family. "It's closure. We're going to take his remains and go to Elk City and put him close to his sister."
Hammack said that even though his family had mostly accepted that Clebern was dead, the discovery was "bittersweet."
"We're glad we found him," he said. "Some of my cousins have talked about maybe having his bones cremated and putting him with his mother so that she finally has him."
Authorities are still investigating how the cars may have gotten into the water and whether there may have been foul play involved. A Google satellite map view of the area where the cars were discovered just three feet apart does not show any roads very close to the water. Officials believe the cars might have gone into the water a year-and-a-half apart.
The cars were discovered when Oklahoma Highway Patrol's lake patrol division was testing new sonar equipment last week in Foss Lake in Custer County, Okla., when they detected some unusual echoes that indicated the presence of large metal objects under the water.
Three feet away, they found a second car with more skeletal remains in it. They have since recovered six skulls and matching bones.
Custer County Sheriff Bruce Peoples said the second cars might belong to Jimmy Williams, 16, who was reported missing in 1970. His car was a 1969 blue Chevrolet Camaro, which looked similar to one of the cars that were recovered.
He was last known to be driving around with his friends Thomas Rios, 18, and Leah Johnson, 18, and none of them have been seen since.