SALT LAKE CITY, Utah (KSL.com) — Idaho authorities have found the cellphone of a 17-year-old girl who, along with her 7-year-old brother, has been missing since September.

The latest update in the ongoing, bizarre case of Tylee Ryan and Joshua “JJ” Vallow, missing from Rexburg, Idaho, was first reported Monday by CBS News. A source close to the investigation told CBS News the phone had been found.

The phone allegedly was used several times after Tylee disappeared, CBS News reports. On Oct. 25, a text was sent out from the phone that read “hi. miss you guys too …luv ya.” The person who got the text, a friend of Tylee’s, said it didn’t sound like something Tylee sent, CBS News reported.

Two small Venmo payments also were sent from the phone to a family member in October, according to CBS News.

Lori Daybell, the mother of Tylee and JJ, is believed to have been in Hawaii for the last two months with her new husband, Chad Daybell. The case has attracted public interest and media attention across the country.

Both Lori and Chad Daybell have been named persons of interest in the disappearance of the two children, but neither has been arrested or charged. Police say the couple has not revealed any information about where the children are.

The Daybells were served with two search warrants last month in Hawaii, according to EastIdahoNews.com. Authorities seized the couple’s SUV and searched a townhome in Princeville, Hawaii.

Also last month, Lori Daybell was ordered to produce the children by Jan. 30 or possibly be found in contempt of court. There is still no sign of the children.

In another recent development, Lori Daybell apparently abandoned a Rexburg storage unit in November that was full of children’s items, photos and clothing.

Chad Daybell has self-published several books that detail doomsday scenarios and near-death experiences.

Police are also investigating the suspicious death of Chad Daybell’s former wife, 49-year-old Tammy Daybell. Police have said they believe her death is related to the disappearance of Tylee and JJ, but have not said how.

Lori Daybell’s estranged husband, Charles Vallow, was shot and killed in July by her brother, Alexander Cox, in a family fight. Cox died in Arizona in December. The two deaths are active investigations, according to authorities in Arizona.

Other family members have offered a $20,000 reward for information leading directly to the recovery of Tylee Ryan and JJ Vallow.

Dr. Oz will air a program Tuesday focusing on the Daybell case, according to EastIdahoNews.com. Kay and Larry Woodcock, grandparents of the children, are scheduled to appear.

EastIdahoNews.com News Director Nate Eaton, who has been reporting the case from Idaho and Hawaii, also will appear on the show.