A Wealthy Mom Vanished Alongside Two Teen Girls in Yosemite National Park — Later, a Serial Killer Drew a Map to a Corpse By Virginia Chamlee

When Carole Sund, her 15-year-old daughter Julie, and her teenage friend Silvina Pelosso set out to Yosemite National Park in February 1999, they were planning a tour of one of America’s wonders. Silvina – an exchange student from Argentina — was staying with them for three months and was eager to see the wonders of America. So, following a trip to Julie’s cheerleading competition in Stockton, the three set out for the renowned national park.

Carole, 42, had phoned her husband Jens from their hotel — the Cedar Lodge — the evening of Feb. 15. The three had spent the day in the nearly deserted park and planned to return for more sightseeing the following morning, she said.

Later that night, newspaper reports indicate the three ordered hamburgers at the hotel’s restaurant when Carole abruptly paid their $21.13 dinner bill. They all left, indicating they would return to finish their meals.

They never did.

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The three were set to arrive home after 10 p.m. the next night, on Feb. 16. But when Jens arrived at the commuter terminal at San Francisco International Airport, his wife Carole, his daughter Julie, and their friend Silvina were nowhere to be seen.

Initially, he didn’t panic, thinking perhaps he had misunderstood Carole’s instructions.

“I really didn’t think anything was wrong,” the property manager from Eureka, Calif. told PEOPLE in a 1999 interview. “We had never had anything bad happen to us.”

But the following afternoon, with no word from Carole, Sund called her parents, and learned they hadn’t heard from her either — and then discovered Julie had missed an appointment to tour the University of the Pacific in Stockton, which she hoped to attend.

So just after 7:30 p.m. one day after the three were to have arrived home, Jens called the California Highway Patrol.

A search began immediately, with PEOPLE citing sources at the time who explained that family members (including Jens) were quickly dismissed as suspects after being given lie detector tests.

Four days later, a clue surfaced when a pedestrian walking in downtown Modesto on Feb. 19 found part of Carole’s black leather wallet, including her ID and credit cards, on a roadway some 90 miles west of the Cedar Lodge, where they had last been seen.

More than a month later, there was still no sign of the three, and other clues were scant with FBI special agent James M. Maddock explaining to PEOPLE that the disappearance had set off one of the largest missing persons searches in California history.

As Carole’s family offered a $300,000 reward for information on her whereabouts and dozens of relatives had joined in the search, the FBI announced they suspected the three had been victims of a violent crime committed at or near their hotel.

“With the FBI saying they’ve got to be dead, it’s been tough,” Carole Sund’s mother, Carole Carrington, told PEOPLE at the time. “But we must just think they’re alive — we just must.”

On the surface, the women seemed unlikely victims.

Relatives noted that Carole — who also shared three younger children with her husband — stocked her car with emergency supplies and once gave a friend a gift of pepper spray for Christmas. “My daughter is a survivor,” Carole’s father, Francis Carrington, the founder of a multimillion-dollar commercial real estate firm, told PEOPLE at the time. “If there’s any chance to be alive to protect those girls, she will be.”

Her daughter, meanwhile, was a key organizer of a teen support group called Girls Against Violence.

Just weeks after PEOPLE published its report on the disappearance, in March 1999, Carole’s rental car was found — and inside it, the charred remains of both she and Silvina’s bodies. Juli Sund remained missing.

Shortly after that discovery, an FBI agent in the Modesto, California, office, was sent a crudely-drawn map purporting to be from the killer.

“It says, ‘We had fun with this one.’ And we think that fun means something of a sexual nature that’s not good for the victim,” former FBI agent Jeff Rinek told ABC News. “There’s a crude map, and the map shows Route 120. It shows Vista Point. It shows Don Pedro Reservoir, and it’s about forty miles away from where the car was found.”

FBI agents did indeed find Juli’s body using the map, eventually focusing on a pair of half-brothers from the Modesto area with long criminal histories. But then another victim was found — a 26-year-old Yosemite naturalist named Joie Ruth Armstrong, who was found beheaded.

One week later, Cary Stayner, a 37-year-old maintenance worker at the Cedar Lodge who had been living and working there throughout the investigation, confessed to killing Armstrong and, eventually the three others. He is suspected of potential involvement in other unsolved murders.

Cary was the older brother of Steven Stayer who, at age 7, had been kidnapped and held captive for seven years. His story captivated a nation and led to the 1989 release of a television miniseries based on his experience, I Know My First Name Is Steven, and eponymous true crime book. He died in a motorcycle accident that same year.

Stayner was convicted in both state and federal courts. He was sentenced to death in December 2002 and remains on death row at San Quentin State Prison.