JACKSONVILLE, Fla. – Years after their disappearances, the families of local missing children continue to climb to the hope that they’ll be reunited with their loved ones someday.

More than 424,000 children were reported missing in the U.S. in 2018, according to FBI figures. Over the years, hundreds of kids have vanished from Florida. Many of those cases remain unsolved.

As we've learned from new developments in several high-profile missing children's cases, sometimes families find the closure they're desperately looking for, but it doesn't always turn out that way.

That's the story in the case of Timmothy Pitzen, who disappeared in Illinois nearly eight years ago after his mother took her own life. On Wednesday, a teen turned up in Kentucky, saying he was Pitzen and he'd been held captive for years by two men. Sadly, investigators debunked that theory on Thursday.

On the other hand, a Utah girl who'd been missing for a year was found safe Wednesday in Lake City. Authorities said Ariana Bozeman was kidnapped by her mother, who had lost custody. Bozeman has now been reunited with her father, who's mapped out a road trip back home so the two can reconnect.

In the Jacksonville area, several cases still remain unsolved. Cases like that of HaLeigh Cummings, a Putnam County girl reported missing from her Satsuma home when she was just five years old. Or that of Mark Degner and Bryan Hayes, who were ages 12 and 13 when they disappeared from Jacksonville.

SPECIAL COVERAGE: HaLeigh Cummings disappeared 10 years ago

These are cases that boggle the mind as all three children seemingly vanished without a trace. Now, America's most prolific real-life crime fighter is examining the evidence in their cases in search of the answers that have eluded loved ones for more than a decade.

Degner & Hayes

Mark Degner and Bryan Hayes vanished in February 2005 after they walked out of Paxon Middle School on Jacksonville’s Westside. They haven’t been seen since, leaving their families heartbroken and anxious to this day.

"It’s hard, you know?" said Linda Holland, Mark’s mother. "When you think about it, you start crying. And you try to be brave for your kids. Because I have other kids. And I try to be brave for them to make them not feel as bad."

HaLeigh Cummings

Exactly four years after the two Jacksonville boys went missing, another unsolved mystery gripped the Northeast Florida community and the nation as a whole.

HaLeigh Cummings was five years old when she was reported missing from her Satsuma home. Her father's girlfriend, Misty Croslin, was looking after HaLeigh at the time.

She told investigators she woke up to find the back door of the family's home propped open with a cinder block and HaLeigh gone.

Investigators spent years looking for HaLeigh, with their efforts taking them as far away as Nebraska as they chased down every lead. But despite rampant speculation and rumors about what happened to the girl, the case eventually ran cold. Though she's presumed dead, her loved ones remain hopeful.

John Walsh's mission

As the years go by, the tips and leads become fewer and farther between. America’s top TV crime fighter, however, hasn’t forgotten about the cases.

"I say never give up," John Walsh said. "The National Center [For Missing and Exploited Children] never gives up. I never give up on missing children. I have broken some of the longest term cases and gotten them back."

News4Jax spoke with Walsh about keeping local cases alive. He hosted “America’s Most Wanted” on Fox from 1998 to 2012. He now hosts “In Pursuit with John Walsh" on Investigation Discovery.

Walsh grew to fame in 1981 when his son Adam, 6, was abducted from the Hollywood Mall in South Florida. The body was found murdered two weeks later. Police officially closed the case in 2008, linking the slaying to deceased serial killer Ottis Toole of Jacksonville.

"And of course we're dying of broken hearts, but we’re opening that mail for months and months," Walsh said. "It was people that had runaway kids, people who had missing children, people who had murdered children, people who had been victims of non-custodial parental abduction -- [there was] nothing to help them."

That’s what inspired Walsh and his wife, Revé, to start the Adam Walsh Center, which became the National Center for Missing and Exploited Children. It’s headquartered in Virginia, just outside of Washington, D.C., but it has regional offices across the country.

In March, they opened a nationwide tipline call center, 1-800-THE-MISSING, based in Palm Beach County, the site of the original Adam Walsh center. There, case workers know every call could be the big break investigators need. Callers can remain anonymous.

Families find hope

“​When Kamiyah was found, you know, obviously we were ecstatic,” said Bob Lowery, NCMEC’s missing children’s supervisor.

Lowery remembers getting the tip that led police to Kamiyah Mobley. She was abducted as an infant from a Jacksonville hospital in 1998 and discovered 18 years later living under the alias Alexis Manigo with her abductor in South Carolina.

Mobley’s case brings hope for the families of HaLeigh, Mark, Bryan and so many more missing kids.

"Never give up hope," Lowery said about families who still don’t have answers about their missing loved ones. "We've seen remarkable stories like this in the past."

He's talking about stories like that of Elizabeth Smart, who was abducted in 2002 and found in 2003, and Jaycee Dugard, who was kidnapped in 1991 and found in 2009.

Age progression

The NCMEC uses a talented team of artists for age progression. The organization provides the service free of charge to law enforcement agencies investigating missing persons cases.

Age progression renderings show what Degner and Hayes could look like in their mid-20’s. The team just refreshed a simulated picture of HaLeigh Cummings, who would now be 15 years old.

"We consider these age progessions beacons of hope for these families," said Collin McNally, age progression supervisor for NCMEC.

"As long as a child is still out there, we’ll update these every two years," he added. "After they turn 18, we’ll update them every five years."

Never give up

For the local families still without answers, giving up is not an option.

“I just hope that one day they’re going to come to the door and say 'I am here, I’m alive, I’m OK," said Degner’s mother, Linda Holland. "I love him. And no matter what he has been through or he has gone through, I just want him to be be safe and sound. To see his face for once."

Who do you call?

To learn more about NCMEC and missing childrens cases, go to MissingKids.org. If you think you have seen a missing child, contact the National Center for Missing & Exploited Children. It's open 24 hours a day, seven days a week. The 24-hour hotline is 1-800-THE-LOST (1-800-843-5678).