Hulu documentary looks at how missing woman's case sparked an investigation into possible serial killer

On New Year's Day 2008, Meredith Emerson went for a hike in Georgia's Vogel State Park with her dog, Ella.

She never returned.

As investigators searched high and low for the 24-year-old sales manager along the trails on Blood Mountain, Georgia, they uncovered a possible connection to other missing hiker cases that were recently reported in the South -- and a frightening suspect.

An ABC News Studios four-part docuseries, "Wild Crime: Blood Mountain," explores Emerson's case, telling the story from the perspective of the investigators and key players who raced to solve the mystery of Emerson’s disappearance.

Georgia Bureau of Investigation special agents John Cagle and Clay Bridges said that Emerson's disappearance was strange to her friends and family because she was an experienced hiker who had hiked Blood Mountain’s trails in the past.

After word got out about Emerson's disappearance, Cagle and Bridges said they received a number of tips from witnesses who saw Emerson and her dog on the trail. Several witnesses said they saw a mysterious man hiking directly behind her.

"The guy he described was a man in his 50s or 60s. He was wearing high-end hiking gear, he had a police-style baton and he had a bayonet knife on his belt," Bridges said. "What [one witness] couldn't shake was the fact that he had duct tape on his shoes. Somebody is a very experienced hiker; why would you have duct tape on your shoes?"

One of the witnesses took a picture of the man, who was wearing a yellow jacket and standing near a white van.

"We knew we were on the right track, uh, because of the consistency of all those witnesses that we wanted to find this man," Cagle said

Two days after Emerson's disappearance, the Georgia investigators said they got a call from investigators in North Carolina that got them more concerned about their case.

Harold Young Jr., now a retired special agent with the United States Forest Service, said he was investigating the disappearance of John "Jack" Bryant, 80, and his wife Irene, 84, who went missing while they were hiking in North Carolina's Pisgah National Forest in October 2007. The couple were also experienced hikers.

Less than a month later, on Nov. 10, the remains of Irene Bryant were found. Jack Bryant was still missing.

Young said that he had interviewed some witnesses who were in the park the same day that the couple was last seen and some described a man with a police baton who had a white van.

"This started to paint a picture to me. I'm dealing with somebody who is here constantly. He's making the effort to make some kind of contact with the potential victim or victims," he said. "And, unfortunately, for whatever reason, the Bryants turned into a victim."

Cagle said he and his investigators also got word from authorities in Florida who told them of a 2007 missing person case in Apalachicola National Forest near Tallahassee. On Dec. 3 of that year, Cheryl Dunlap, 46, who worked as a nurse, was reported missing after she didn't report to her job.

Her car was later found abandoned on the side of the road.

On Dec. 15, 2007, a hunter who was hiking in Apalachicola National Forest found the remains of a body without a head. A DNA test would confirm the body was Dunlap's.

Investigators had little to go with in their pursuit of a suspect, other than reports of a person who was seen using Dunlap's ATM card shortly after her disappearance.

"You're dealing with hundreds and hundreds and hundreds of miles of national forests. We know of no witnesses to how her body got there, so there's nobody to interview on what they saw," said Tim Baxter, a retired lieutenant for the Leon County Sheriff’s Department who investigated Dunlap's murder.

Cagle and Bridges said the similarities in the Florida and North Carolina cases concerned them, and they were determined to find any signs of Emerson.

They caught a break when a man named John Tabor called investigators after hearing about the person of interest in Emerson's disappearance. Tabor said that the man described by police looked like one of his former employees, Gary Michael Hilton.

Hilton, who had a few misdemeanors in his criminal record, had been aggressive at times, according to Tabor.

"Tabor described Hilton, though, toward the end of his employment, as being very volatile and, kind of scary, so firing Hilton was a real good idea," Cagle said.

Investigators then released Hilton's picture and name to the public as part of their investigation into the Emerson case and were soon contacted by Samuel Rael, an attorney who had represented Hilton for relatively small matters in the past.

Rael revealed that he and Hilton also worked on a low-budget, direct-to-video movie "Deadly Run," about a serial killer who hunts women in the woods.

"As soon as I mentioned serial killer, Gary [Hilton] just couldn't wait to be of help and couldn't wait to do anything and everything that would help make the movie," Rael said.

Cagle and Bridges said their concern about Hilton intensified as they increased their efforts to find Emerson. The ensuing investigation included looking deeper into Hilton’s background, and trying to discover if he had any connection to the Bryants, Dunlap or the disappearance of Meredith Emerson.

A question lingered: Was Hilton just interested in true crime or might he himself be a serial killer?

"I wanted to find Meredith and return her to her parents. That's all we all wanted to do," Cagle said.

"Wild Crime: Blood Mountain" is now streaming on Hulu, a division of Disney, ABC’s parent company.