Challenges ahead as investigation into JJ Vallow and Tylee Ryan's death continues

Thursday marks two days since investigators discovered two sets of human remains in the backyard of doomsday author Chad Daybell, the man who married the mother of Joshua "JJ" Vallow and Tylee Ryan, two children with Arizona ties who disappeared in 2019.

JJ and Tylee were last seen in September 2019. On Wednesday, family members confirmed the remains are those of the children.

JJ and Tylee's disappearances have uncovered a complicated sequence of events related to their mother, Lori Vallow, and Chad, Lori's new husband. They including details surrounding the death of Lori's former husband, Charles Vallow, details surrounding the death and subsequent burial of Chad's former wife, Tammy, and details of unorthodox religious beliefs, including allegations of cult membership

The children's mother, Lori Vallow, was married to Chad Daybell shortly after both their spouses died. Lori's late husband, Charles Vallow, was shot dead in July 2019 by his brother-in-law, now identified as Alex Cox. Cox died in December 2019. Chad's first wife, Tammy Daybell, died in October 2019, and Idaho's Attorney General's Office is taking over the prove into her death.

Family members of Tammy Daybell speak out

On Thursday, the family of the late Tammy Daybell released a statement. The statement is released by her parents, siblings and relatives, and not Tammy's children.

The statement reads:

"We share the pain of the tremendous and shocking loss you are enduring. We still suffer and we will suffer with you for many years to come. Please know we will continue our prayers to strengthen your families, as you are finally able to properly lay to rest your precious Tylee and JJ."

Neighbor notified authorities

On Thursday, Matthew Price, who lives in the area, told FOX affiliate KSTU in Salt Lake City that he notified authorities of what he has seen in Daybell's yard.

"We noticed they were having a few bonfires that were out of the ordinary," said Price. "They had a big bonfire last fall. Had two or three big bonfires this spring."

That tip ultimately lead to the search warrant executed and Daybell's arrest.

Medical experts detail challenges that lie ahead for investigators

As the investigation continues, new questions are emerging. Questions like when and how did the two children die, and how long have the remains been buried. On Thursday, FOX 10's Justin Lum spoke with a medical expert on what investigators are up against.

"If there’s fire, thermal destruction of evidence, it’s certainly going to complicate things at this point, depending on what occurred," said Dr. Burton Bentley, CEO of Elite Medical Experts.

Dr. Bentley works as a medical consultant in Tucson. He says the weather in rural Idaho, and how the bodies were disposed and buried, will factor into the next part of the investigation.

"These factors are all going to come into play, but if a relatively preserved body -- let's say that it’s wrapped, is put into the ground, it is cold out and we’re getting into winter, things can remain fairly remarkably preserved for a period of time," said Dr. Bentley.

Dr. Bentley says what investigators found in the ground may be compelling and accurate evidence on such a large property. He believes preliminary findings will be released soon.

"I think everybody agrees something hasn’t felt right with this case since day one," said Dr. Bentley.

Tammys autopsy has not been released
The idaho attorney general is investigating chad and lori for conspiracy, attempted murder and or murder
No charges have been filed