A lonely stretch of foggy California coastline is what some think of as a doorway to Heaven on Earth -- others as a gateway to Hell.

Dead bodies, unsolved murders and missing-persons cases. Most disturbing of all are the mysterious disappearances of five young women in one county alone, leaving baffled police unsure whether they're dealing with a serial killer -- or something else altogether.

But now a grim discovery has produced the first break in the case, linking two of the missing women to one man, and bringing grieving parents at least some hope that they may finally learn what became of their daughters.

Humboldt County, California contains quaint little country towns dotting lush, green valleys fed with rain and sunshine that nourish precious multimillion-dollar crops.

"We're known throughout the country for our marijuana," said Fortuna Police Officer Brian Taylor.

The area is called the "Emerald Triangle," the epicenter of the American pot industry, encompassing Humboldt, Trinity and Mendocino counties, a few hundred miles north of San Francisco. And right in the middle of that triangle is a place that's come to be known as "Murder Mountain."

"It got its name from a serial killer several years back, and since then there's been several other people who've been murdered there," said Brenda Condon, president, Cal Advocates for the Missing.

But no case has been as baffling and disturbing as that of the so-called "Humboldt Missing Five": Five young women who have all mysteriously vanished in Humboldt County over the past two decades, leaving police without a clue to what happened to them. That is, until the fifth woman, beautiful 23-year-old Danielle Bertolini, went missing.

Danielle had just moved to Fortuna from Maine, lured by the natural beauty of Northern California. And her mom, Billie Jo, who's been traveling here from Maine to search for her daughter since she went missing two years ago, says Danielle seemed to feel right at home in Fortuna.

But Billie Jo says that like many other young people in the Emerald Triangle, Danielle had gotten involved with drugs before she disappeared. And Danielle's mom had been begging her to get away from the area and return home to Maine.

Billie Jo would next learn that Danielle was nowhere to be found after last being seen getting into a car on a road leading to her home. And Danielle's disappearance gives police their first break in the case of the "Humboldt Missing Five" when they discover the man driving that car was the boyfriend of another woman who disappeared just a week earlier.

It was as if they had all simply vanished into the fog of the Emerald Triangle.

Police hadn't been able to find a clue to what happened to any of them since all of these young girls began going missing back in the 1990s.

After the first two young women disappeared -- Jennifer Wilmer and Karen Mitchell, both 16 -- cops thought a serial killer might be on the loose.

The now-infamous millionaire and accused killer, Robert Durst, potentially linked, police say, to the murder or disappearance of at least three people, and subject of HBO's groundbreaking six-part series "The Jinx," was also reported to frequent a homeless shelter where Karen Mitchell volunteered. He was a somewhat regular customer at her aunt's shoe store, one of the last places Karen was seen alive. But there are reports Durst wasn't even in the area at the time.

Then there was confessed serial killer Wayne Ford, who admitted to murdering and mutilating four other women. But he denied killing Karen Mitchell.

Other young women continued to disappear while Ford was behind bars.

It wasn't until early 2014, when Danielle Bertolini vanished, that police would get what could be their first break in the 20-year-old case of the Humboldt Missing Five.

Danielle, 23, had been given a ride in Fortuna by a man named Jim Jones, who told police he had dropped her off near her house. But now cops had something to go on, because they could link Jim Jones to the disappearance of another woman, 37-year-old Sheila Franks just a week earlier.

"James Jones was involved with Sheila and was the last person to see Danielle," said Fortuna Police Officer Brian Taylor.

Sheila, the divorced mother of two sons, had been dating Jones for several months and was actually living with him when she disappeared, according to Sheila's older sister, Melisa Walstrom.

"When he was questioned about my sister, he told police that he and Sheila were at the house and she decided she wanted to go for a walk, and she just left walking, and the last time he had seen her was at the end of the road," said Walstrom.

Which made Jones the last known person to see both Sheila and Danielle alive.

"At this point he's a person of interest, but there's not enough at this point to say yes, he is our primary suspect," said Officer Taylor. "He has come in and interviewed and cooperated to some extent."

In an astounding development, Crime Watch Daily learned Jones had an alleged link to yet another of the Humboldt Missing Five.

Sheila's sister Melissa says Jones also knew Karen Mitchell, the 16-year-old who became the second of the young women to go missing. Karen had last been seen getting into a car in downtown Eureka. But her mother still has no idea if the driver might have been someone she knew.

Melisa says she and Sheila also both knew both Jones, who is now a 43-year-old sawmill worker, when they were growing up in Humboldt County.

"He's lived there all of his life. I went to school with him," said Melisa. She says Sheila reconnected with Jones after the collapse of her marriage.

So Melisa doesn't believe her missing sister would have just got up and left of her own volition, especially after finding all of her personal belongings had been put in storage.

"In the storage unit I found my sister's purse that had money, credit cards, it had a birth certificate, marriage certificate, everything that my sister had that was important to her, she wouldn't up and disappear and not take money at least," said Melisa Walstrom.

Sheila's best friend Brooke Nelson agrees: "She wouldn't have left her boys. She wouldn't have just disappeared. Not willingly." Brooke says Sheila had confided in her that she was having trouble in her relationship with Jim Jones.

"Sheila had told me that she had stopped the relationship as an intimate one and told him she'd live with him, be a companion, someone to lean on, a friend. But she did not want to be romantically involved with him," said Brooke.

Melisa says friends saw signs just a week before Sheila disappeared that she may have been beaten by Jones, who has a criminal arrest that includes arrests for drugs and a conviction for domestic violence.

"She was like, 'Well, Jimmy and I got in a fight and he punched me, gave me a black eye,'" said Melisa.

Police had no evidence to prove any harm had even come to any of the Humboldt Missing Five until just last year when a skull was found in a local riverbed. It was determined to be that of Danielle Bertolini, who is now presumed to have been murdered and most likely mutilated.

Crime Watch Daily paid Jim Jones a visit at his home to see if he would talk about the case. He declined to speak with us.

Officer Brian Taylor says police still need more evidence to make an arrest.

"I'd say we're a lot further than we were in the beginning, and one piece of evidence could solve the whole case," said Taylor.

And that's why Danielle's mother still regularly joins the families of other missing girls and police to search for more evidence in the area where her daughter's skull was found.

Police say Jim Jones is not a suspect, but a person of interest who cops think may have more information about the disappearance of the Humboldt Five.

Officer Taylor vows he won't stop searching until he can bring the grieving families the closure they need.

If you know anything about the cases of the Humboldt Five -- no matter how small you think it is -- Investigators want to hear from you. Contact the Humboldt County Sheriff's Department, or submit a tip to Crime Watch Daily at (844) 800-CRIME.