Authorities in Idaho may be planning to search Yellowstone National Park for signs of a missing Idaho teenager, as a new report confirms the park is her last known location.

According to court documents obtained by CBS News, Rexburg police say Tylee Ryan, 17, visited the park with her mother Lori Vallow, her uncle, and her 7-year-old brother JJ Vallow on September 8. Police reportedly found a photo of the teen taken at the park that day on her mother’s iCloud account. There are no further confirmed sightings of the missing teen. Ryan’s brother JJ is also missing but was seen later that month on doorbell camera video taken at Vallow’s apartment complex in Rexburg.

A source close to the investigation told CBS News that investigators are considering searching the park for Ryan and are currently waiting for the snow to melt. Park officials reportedly declined to comment, citing the ongoing investigation.

Vallow was arrested last week after being found with her husband Chad Daybell in Hawaii in January. The couple fled Vallow’s Idaho home in late November, after police performed a wellness check and discovered the two children were missing. Vallow has refused to cooperate with the investigation into her children’s disappearance, and failed to meet a court-ordered deadline to present her children to authorities in Idaho in late January.

Relatives of the couple have said they believe both Vallow and Daybell are involved in a so-called end-days cult. Both of their spouses died in 2019; Daybell’s wife Tammy died only weeks before he married Vallow, whose husband was shot to death by her brother Alex Cox in July. Cox was found dead in December of still-unknown causes.

Authorities initially determined that Tammy Daybell died of natural causes, but have since exhumed her body and re-opened the death investigation.

Vallow is in custody in Kauai, and is expected to be extradited to Idaho.

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