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(NewsNation) — There has been a critical new development in the disappearance of Jacob Olivier, a young father in South Florida, with a NewsNation investigation finding that another man went missing in the same national park months before.

Neither case has received much media attention. Jacob Olivier’s truck was found in Everglades National Park in the summer of 2011, but he is not the only person to have vanished there. Another man with strong family ties also went missing on a camping trip a few months earlier.

One million visitors boat, camp and come face-to-face with Everglades National Park’s alligators each year. But Olivier was one visitor who never returned home.

Jacob Olivier disappears

The Everglades are a popular destination, but Olivier’s mother, Laurie Durham, said her son had no ties to the area. She didn’t even know he was there, or that he had gone missing, until a reporter called her.

“I found out from a news reporter that called me and said, ‘are you aware your son is missing in the Everglades?'” she told NewsNation.

Not only did Olivier have no ties to the park, which spans 1.5 million acres, he also didn’t have any connection to the three south Florida counties it straddles.

A Louisiana native, Olivier’s truck was found in the Everglades in August 2011. Rangers began searching the park after noticing the vehicle abandoned for days.

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From the start, Durham said she has received conflicting information.

“First I’m told there’s a video of his truck going in,” she said. “Then I’m told later the video never existed.”

Notes from the National Park Service indicate the 1998 Isuzu pickup was parked near Pine Glades Lake.

Tracing Jacob Olivier’s steps

Durham said as far as she knows, Olivier left from Spring, Texas, in that truck. He’d been living there with his father and stepmother and had gone to rehab in the area.

Olivier then traveled to an area near Savannah, Georgia. It was a place he had once called home, and he was hoping to rekindle a romantic relationship.

But that ex-girlfriend was dating someone new. Olivier took off.

A receipt from a hotel in Daytona Beach, Florida, was found in his truck when rangers discovered it.

Courtenay Yeager, Olivier’s sister, confirmed that he had no connections in the area. She says he would run off from what she described as a rough childhood.

“When my mom told me he was missing, I said he probably just ran away,” she said. “I was in denial. I said he’s going to come back. I was just in shock.”

But Olivier wasn’t the only person to disappear in the park, shocking family members.

Roger Sawyer disappears

Just five months earlier, 67-year-old Roger Sawyer and his extended family stopped their motor home in the Flamingo District of the park in March 2011. They were on their way to visit the Florida Keys.

Sawyer’s family said the group split up for 20 minutes to stretch their legs and hike a bit. Sawyer, who they say was not affected by dementia, never returned.

After a week of intense ground and air searches, the hunt for the retired grocer was called off. It’s not clear whether the man described as an experienced outdoorsman got lost or something caused his disappearance.

No leads in either case

Olivier’s case also remains a mystery. Durham looks back lovingly at memories of her middle son, the happy pictures of his child a sharp contrast to the pain of his disappearance.

Scores of searchers looked for Olivier for a week, using canines and helicopters but finding no trace of him. But she’s not giving up.

“I’m still here and I’m going to keep looking to the last breath I have in me,” Durham said. “I’m not giving up. I will never give up. Until I’m cremated, I’m never giving up.”

NewsNation reached out to Everglades National Park’s law enforcement team for information on both cases. They referred us to the national spokesperson, where a public affairs specialist referred reporters back to the park.

The chief of communications for Everglades National Park said they are urging people to come forward with pertinent information and both cases are still open.

Public information requests for details were denied.

Jacob Olivier would now be 36 years old and Sawyer 81.