This has been in the news for a while. The last known place the children were seen alive was Yellowstone National Park. After that there is no known information as to where the children are other than the mother said the children were with a relative. The relative has said she has no idea of the whereabouts of the children at that the mother had not brought them to her.
Child Protective Services in Idaho served papers on her to produce the children to show that they were okay after it was believed that they were missing. She then ran off to Hawaii with her new boyfriend. She was arrested on a warrant from Idaho to be held for extradition. She is now back in Idaho.
They're trying to get pictures from people that may have seen them in Yellowstone to get a timeline and location of where the children may have actually been seen last in the park so they can start looking for their bodies.
There is a lot of strange things going on around this woman and her boyfriend. She read some books that he wrote about the end times. She ran off the Idaho leaving her second husband to have an affair with the man. He is a member of a doomsday cult.
There has been a high mortality rate of relatives and Children of the cult members. The woman's first husband who was the father of the children supposedly died of natural causes. Her second husband was allegedly killed in self-defense by the woman's brother who is also now dead. The boyfriends wife also supposedly died of natural causes. The body of the husband and the body of the boyfriends wife are being exhumed and reexamined.
The woman originally lived in Arizona when she was married to her first two husbands. She then moved to Idaho with the children after the death of her second husband.
The son is autistic. The son had a trained therapy dog. The woman return the dog to the organization that had provided it saying that he no longer needed the dog and do not mention it to the daughter before moving to Idaho. Items belonging to the children have been put in a rental storage unit. The daughter's cell phone was used in Hawaii and there is no evidence that her or the boy ever travelled to Hawaii.
I think based on her lack of cooperation and not being able to find the children I think it's pretty well believed that they are deceased.