On May 5, Gary Simpson took his niece, Carlie Trent, out of school, collecting the 9-year-old "under false pretenses," according to the Tennessee Bureau of Investigation.
Authorities have been searching for her ever since.
In the days that followed Simpson's and Trent's disappearance, investigators have received hundreds of tips. They've released video footage, and pictures of items that Simpson bought before picking up the girl.
But Carlie remains missing, and, according to Josh DeVine, a Tennessee Bureau of Investigation spokesman, is believed to in "imminent danger".
"Gary, if you're out there, we would encourage you to do the right thing . . . we would encourage you to bring Carlie home," DeVine said this week in comments directed to Simpson, according to the Knoxville News Sentinel. "There is nothing that has happened in the past few days that cannot be discussed and can't be worked out."
Carlie's father, James, told the Kingsport Times-News that Gary Simpson, 57, was a "very trusted member of the family," someone who had previously picked up his children. Simpson, who is related to Trent by marriage, lives next door to the family, according to the newspaper.
"He sees those kids every single day," James Trent told the Times-News. "I just don't know what would possess him to do such a thing except just evil."
The TBI yesterday released pictures of items that Simpson had purchased at a local Walmart before taking Carlie from her Rogersville, Tennessee, school - items that included underwear, a child's nightgown, nail polish and a two-piece bikini.
The agency has also released video captured on a surveillance camera after Simpson picked up the child from her school, according to the TBI.
Investigators think that Simpson and Carlie, who are believed to be travelling in a van, might be in an "isolated area," like a campground, according to a news release.
"There's every indication that he intended to go out of sight," DeVine said, according to the Knoxville newspaper.
An Amber Alert has been issued, and rewards offered for information that leads to Carlie's return.
"Bring her home," James Trent told the Times-News. "Bring her somewhere. Drop her off someplace. Anything. Just let her go. He'll have to deal with this thing in due time, but my goodness, for God's sake let her go."