The Tennessee Bureau of Investigation said in a news conference Monday that it was moving its command post in the search for Carlie Trent to Rogersville, TN, to be closer to officers there.

Carlie was taken from school last Wednesday afternoon by Gary Simpson, her uncle who previously had custody of the 9-year-old.

A TBI spokesman said Simpson told school officials when he picked up Carlie at school that she would be absent on Thursday but be back on Friday.

Simpson previously had custody, but it had recently been awarded to Carlie’s father. The school system had not been updated on the change of custody, so Simpson was allowed to pick up the girl.

The TBI issued an endangered child alert on Wednesday and escalated it to an Amber Alert on Thursday morning after Rogersville police filed a kidnapping warrant against Simpson.

“We have imminent concern about this child’s well-being,” said TBI spokesman Josh Devine.

Devine said the TBI had received only 150 tips concerning Carlie.

“Traditionally when we have an Amber Alert, the phone rings off the hook,” said Devine. “That is not the case with the Carlie Trent situation. The lack of phone calls leads us to believe Carlie and Gary Simpson are in an isolated area.”

During a briefing on Monday night, Devine said the number of tips had increased to more than 500 tips.

Devine also spoke directly to Simpson, asking him to come forward and bring Carlie home.

The TBI released video showing Simpson at an area Wal-Mart purchasing outdoor gear before he picked up Carlie from school.

A later video released from Wednesday showed Carlie and Simpson in a Save-A-Lot grocery store purchasing non-perishable food.

Authorities believe Carlie and Simpson may be in an isolated area.

The TBI said Simpson is not an experienced criminal and could be low on money. He is unemployed and had not stockpiled any cash, so investigators said he may have nowhere to go.

They were believed to be in a white 2002 Dodge van with Tennessee license plates 173 GPS.

The TBI urged anyone who spotted the van, Simpson or Carlie to call 911 first to allow local enforcement to reach the scene before they could leave.

Authorities also suggested people who own large amounts of land in the area should check their land in case Carlie and Simpson are camping there.

If you have information, you can also call 1-800-TBI-FIND.

The TBI also said the Amber Alert has not been expanded to other areas. Devine said there isn’t a national Amber Alert system and they did not have credible information to believe Carlie and Simpson had moved to another state.