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While it’s been six days since his 9-year-old daughter Carlie disappeared, James Trent is trying to stay positive.

“I have to be strong for my other daughter and for Carlie,” James told Dateline. “But as the days keep passing, it’s getting harder.”

Carlie was picked up Wednesday, May 4, from her Rogersville elementary school by her uncle by marriage, Gary Simpson. Simpson, 57, previously had custody of Carlie and her younger sister, but that had since been returned to her biological father, James.

An AMBER Alert has been issued for Carlie Trent (right) who was picked up from school by her uncle Gary Simpson (left) on May 4th. Tennessee Bureau of Investigation

James is a single father, and he says Simpson regularly helps out, picking his daughters up from school for appointments or events if he had to be at work.

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But there were no plans for Simpson to pick up Carlie that day, and neither of them has been seen or heard from since.

The last images show the pair inside a grocery store that Wednesday evening with her uncle, stocking up on non-perishable items and treats.

Earlier that same day, surveillance video from a nearby Walmart showed Simpson purchasing camping gear, leading officials to believe he perhaps took the young girl to a remote area. Simpson was last seen driving a white 2002 Dodge Conversion Van with Tennessee registration 173GPS.

“There are so many places he could be,” James said. “I don’t know what story he’s told her, because there is no doubt she wants to be home. This whole thing has puzzled our whole family because everything about that morning was normal.”

After casting a statewide search, the Tennessee Bureau of Investigation (TBI) announced Monday that they are shifting more resources back to Rogersville, noting the area is the epicenter of the search because both Carlie and Simpson are from there. "It's a bit like a needle in a haystack," TBI spokesperson Josh DeVine told NBC affiliate WBIR. “We need the public to remain vigilant. We really believe that it is going to a good-natured citizen that is going to crack this thing wide open.”

The outpouring of support for Carlie’s family has been immense. Her photo has been leading nightly newscasts across Tennessee for days, and thousands of people have been sharing missing person fliers online and posting well wishes. Carlie’s pediatrician is offering a $10,000 reward for information leading to her safe recovery and the U.S. Marshals Service has also announced a $2,500 reward for the same.

All that is a comfort for James. “Someone seeing her is going to be the key thing here,” he says.

Although James doesn’t think Carlie can see any of this attention, he wishes he could get one message to her.

“I want her to know that she’s loved. That she shouldn’t believe whatever he’s telling her. She should get out, run, scream, do whatever she has to do to get away, because there are so many people looking for her. We’ll never give up.”

Carlie Trent is described as 4’8” tall, weighing 75 lbs. with blonde hair and blue eyes. She was last seen wearing a black and grey tank top with blue jeans. Gary Simpson was last seen wearing a brown cap, dark colored shirt and blue jeans.

Anyone with any information regarding Carlie or Simpson’s whereabouts is urged to call the Rogersville Police Department at (423) 272-7555 or the Tennessee Bureau of Investigation at 1-800-TBI-FIND.