Using a phony name and claiming he was researching wealthy Floridians to learn about their work habits and personalities for a psychology dissertation, Gary Krist visited the Miami Public Library in the fall of 1968 and pored over the names of the social register.

His eyes landed on one name in particular — one that would be familiar even today to many Volusia County residents.

Robert Mackle was a wealthy real estate developer who along with his brothers created Deltona. The city’s swirling street design was a Mackle signature, and one of its main thoroughfares still bears the family name — spelled backwards.

Most importantly for Krist’s purposes, Mackle had a pretty 20-year-old daughter, Barbara.

Krist’s research that day would result in one of the most elaborate kidnapping plots in FBI history. As documented in newspaper archives and other written accounts, the crime elicited the attention of President Nixon, who was personally known to Robert Mackle. FBI Director J. Edgar Hoover would dispatch the man who’d investigated both Kennedy assassinations to oversee the case. A first attempt to hand over the $500,000 ransom would be accidentally thwarted, and Krist, knowing he had the FBI on his tail, would boldly set up a second ransom drop, which succeeded.

All the while, Barbara Mackle would remain buried underground for 83 hours, her fate unknown.

Real estate giants

The Mackle family, consisting of brothers Frank Jr., Robert and Elliott, forever altered the landscape and demographics of Florida.

Their General Development Corp. was the largest land development company in Florida for a time, and they turned thousands of square miles of swampland and thick woodland into sprawling residential communities for the middle class. One of the Mackle brothers' biggest achievements was Deltona, the community they created in 1962. They also developed Marco Island and Port St. Lucie, among others.

They had high hopes for Deltona from the outset, said author-historian Jason Vuic, a Florida native who is writing a book about Florida's land development giants from the early second half of the 20th century.

"They had this wonderful stretch of beautiful oak land ... with lakes," Vuic said. "It was completely virgin land, and they built this entire community known as Deltona."

The Mackles predicted in a 1981 News-Journal article that Deltona would have a population of 75,000 within 20 years. It would take 40 years, but the city is now the biggest in Volusia County.

83 hours in a hole

In the early morning hours of Dec. 17, 1968, Barbara Mackle, sick with the flu, was staying in an Atlantia-area hotel with her mother, Jane Mackle, when Krist knocked on their door, claiming to be a police officer. Once inside the room, Krist and his girlfriend, Ruth Eisemann-Schier, who was wearing a ski mask, bound and gagged Jane Mackle and forced her daughter at gunpoint into the back of their station wagon.

They drove her to a remote forest near Norcross, Georgia, and forced the panicked woman inside an underground capsule that Krist had built. It was equipped with a battery-powered fan and stocked with food and water. Krist sealed it, shoveled dirt over it and spent the next three days trying to obtain $500,000 from her father.

Robert Mackle was determined to get his daughter back. Along with agents from the FBI, he got all of the money together, stuffed it inside a suitcase and left it near a bridge in Miami, just like Krist had ordered.

But the drop didn't go smoothly. For starters, Mackle got lost looking for the drop-off spot.

After he finally obtained the money, Krist came upon two police officers during the hike back to his car. The two had no idea who Krist was or that he was the mastermind behind an elaborate kidnapping, but they found him with a suitcase full of money, a rifle and scuba gear.

Krist fled and the police officers opened fire. Krist got away, but he had to leave the money behind. He was badly injured after scaling a fence.

He set up another drop with Mackle, somewhere near the Tamiami Trail, and got his money. As promised, he called the FBI and disclosed where Barbara Mackle was buried. More than a hundred agents took part in the search, some digging with their hands in hopes of finding the burial spot. She was rescued, dehydrated but otherwise unharmed, after 83 hours underground. The FBI agents were in tears as they pulled her out of the ground.

Kidnappers captured

Krist's newfound wealth was short-lived. He bought a boat and took it on the Okeechobee Waterway in hopes of eluding capture. Most every federal law enforcement official surmised that Krist was headed for Bimini, a cluster of islands in the Bahamas.

One FBI agent took a guess that Krist was heading west instead. His hunch paid off; Krist was spotted and captured west of Port Charlotte — ironically, another Mackle development. His accomplice, Eisemann-Schier, was eventually caught in Texas. She was the first woman to be named to the FBI's 10 most wanted list.

Krist was tried in Georgia, where he faced the death penalty. Jurors acknowledged that Krist tried to keep his victim alive and fulfilled his promise to reveal where she was buried. He was sentenced to life and paroled after 10 years. His life afterward consisted of more unlawful behavior and heartbreak, including a prison sentence after he was arrested on a sailboat in possession of $1 million worth of cocaine. He is still living in rural Georgia.

Eisemann-Schier was sentenced to seven years in prison. After her release, she was deported to her homeland of Honduras, where she is now a grandmother.

Barbara Mackle also is alive and was last reported living in South Florida. She co-wrote a book in 1971 with the late Miami Herald reporter and Pulitzer Prize winner Gene Miller titled, "83 Hours Till Dawn." It was later turned into two TV movies. She has never spoken publicly about her ordeal since the publication of her book.

Though forever linked to the kidnapping, the Mackle legacy as developers shouldn't be overlooked, Vuic contends. The family laid the groundwork for a Florida population boom that would cater not just to the upper class but to lifelong government and factory employees who collected their pensions and wished to retire in the sunshine with fishing boats, town cars and golf clubs.

The Mackles gave countless retirees that dream.

"That was the golden age in the '50s, '60s and early '70s," Vuic said. "That's when a retired postman from ... Muncie, Indiana, could come to Florida and, with his pension, buy a house on the water. That doesn't exist anymore.

"The Mackles personified that age more than any other family," Vuic continued. "Their wealth and their stature is why Gary Krist chose them and why, unfortunately, they chose this very pretty and very talented girl to kidnap. That's really the genesis of the kidnapping of Barbara Mackle."

Listen to writer Tony Holt interview author-historian Jason Vuic about the Mackle kidnapping: