The FBI has released a new photo of “cult” mom Lori Vallow's daughter, taken the day the teen was last seen six months ago.

The photo's release Thursday came as Vallow was flown from Hawaii to Idaho, where she faces child abandonment charges in the disappearance of her daughter, Tylee Ryan, 17, and her son, Joshua "JJ" Vallow, 7. She is due in court Friday.

The photo from the FBI shows Tylee holding JJ, who has autism, at Yellowstone National Park in Wyoming on Sept. 8.

The FBI on Thursday also released a second photo taken that day at Yellowstone showing Vallow, 46, with JJ.

Tylee Ryan, 17, holds her brother JJ Vallow, 7, at Yellowstone National Park on Sept. 8. The FBI is looking for both children. (FBI)

Idaho police say Tylee hasn't been seen since the trip to Yellowstone, and that JJ hasn't been seen since Sept. 23.

"An ongoing investigation has determined" that on Sept. 8 Tylee and JJ were at Yellowstone National Park with Vallow, and their uncle Alex Cox, according to the FBI.

Agents said Vallow, Cox and the children traveled there in a Ford pickup with Arizona plates. The FBI made available two photos of the pickup.

The FBI is seeking any photos and video that may show Vallow, Tylee and JJ at Yellowstone.

FBI released this photo of "cult" mom Lori Vallow and her 7-year-old son JJ, taken at Yellowstone National Park on Sept. 8. JJ has been missing since Sept. 23, according to Idaho police  (FBI)

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Vallow arrived in Rexburg, Idaho, Thursday afternoon. She has been held on a $5 million bond since her arrest in Hawaii last month.

A reporter from East Idaho News was at the airport and peppered Vallow with questions about the missing children before deputies drove her away.

Vallow refused to say anything, the news outlet reported.

Rexburg police said the disappearance of Tylee and JJ was related to the suspicious death in October of Tammy Daybell, whose husband, Chad Daybell, 51, married Vallow two weeks later.

FBI says Lori Vallow, her brother and her children traveled to Yellowstone National Park on Sept. 8 in this Ford pickup  (FBI )

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Arizona police also are investigating the death of Cox in December. Five months earlier Cox fatally shot Vallow’s estranged husband Charles Vallow in what Arizona police called self-defense.

The #FBI, @RexburgPolice are asking any visitors to @YellowstoneNPS on 9/8/19 submit multimedia that may show missing kids, JJ Vallow and Tylee Ryan, their mother Lori Vallow and uncle, Alex Cox. Photos/videos can be submitted online at http://FBI.gov/Rexburg.

Members of Vallow’s extended family have been quoted by local media saying that Vallow joined a “cult” with Daybell, a self-proclaimed Latter-day Saint known for his religious books detailing the end of the world.

Many of his books deal with doomsday situations or near-death experiences, including his own, according to reports

Daybell and Vallow were affiliated with Preparing with People, a group that says its mission is to “help prepare the people of this earth for the second coming of Jesus Christ.”

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The group has denied accusations it is a cult.