Killings of Tylee Ryan and J. J. Vallow

No post-mortem or autopsy was performed on Tammy's body at the time, as Chad had declined to do so and the county coroner did not overrule his decision. Two months later, Tammy's body was exhumed and autopsied. The results were completed by February 2021 but have not been made public.

On February 20, 2020, Lori was arrested in Kauai, Hawaii, and charged with desertion and nonsupport of her dependent children. She was extradited to Idaho and transported there by officials on March 5, 2020. On June 9, 2020, police executed a search warrant at Chad's home and discovered the remains of J.J. and Tylee. Chad was arrested later that day on charges of destruction or concealment of evidence. On May 25, 2021, Lori and Chad were charged with the first degree murders of Tylee, J.J., and Tammy.

On February 20, 2020, Lori was arrested by the Kauai Police Department in Princeville, Hawaii, and charged by prosecutors in Madison County, Idaho with two felony counts of desertion and nonsupport of dependent children. She was also charged with three misdemeanors: resisting or obstructing officers; criminal solicitation to commit a crime; and contempt of court. Lori was held on US$5 million bail. She later agreed to be extradited back to Idaho to fight the charges. The judge lowered her bail to $1 million. On May 1, 2020, Lori appeared for a court hearing in Rexburg to request a reduction of her $1 million bail. The judge denied her request. At least two local bond companies were reportedly unwilling to work with her.

On March 24, 2020, NBC News reported on documents showing that Chad and Lori became convinced that Tylee and J.J. were "possessed" and had become "zombies".

On June 9, 2020, police executed a search warrant at Chad's home, where they discovered human remains buried in a purported pet cemetery. Chad was booked into jail later that day on obstruction or concealment of evidence; he was later charged with felony murder. On June 10, his bail was set at $1 million. On July 2, prosecutors dropped two of the charges against Lori – two felony counts of desertion and nonsupport of dependent children – and instead charged her with obstruction or concealment of evidence in regards to her children's remains.

On July 17, 2020, in light of the two felony counts against Lori having been dropped, her bond was lowered by Madison County judge Michelle Mallard. Judge Mallard decided to decrease bond to US$50,000 on each charge, totaling US$150,000, but noted that Chad would still need to post US$1 million in neighboring Fremont County to get out of jail. In addition to the bond reduction, a jury trial for the Madison County charges against Lori was set for January 25–29, 2021. On May 25, 2021, Chad and Lori were indicted on the charge of conspiracy to commit first-degree murder, first-degree murder, and grand theft by deception for the deaths of Tylee, and J.J., and Tammy. Lori was charged with grand theft related to "Social Security Survivor benefits over $1,000 allocated for the care of minors Tylee Ryan and JJ Vallow that were appropriated after the children were missing and ultimately found deceased". Chad was charged with insurance fraud "related to a life insurance policy he had on Tammy Daybell for which he was the beneficiary and received funds after her death". On May 27, 2021, Lori was found incompetent and unfit to stand trial, and her case was stayed. She has since been deemed competent to stand trial after mental health treatment, incompetent, and again competent. Requests from Chad to separate his case from Lori's have been denied. A start date of January 2023 for both trials had been set, but was canceled in November 2022 without a new date being set.

On June 10, 2020, the Woodcock and Ryan families confirmed that the human remains found on Chad's property were those of Tylee and J.J. This finding was officially confirmed by Rexburg police on June 13. Since the children's remains were found, they are no longer considered missing and the investigation is now focused on determining the circumstances surrounding their deaths.

In November 2019, police questioned the children's mother, Lori (Cox) Yanes Lagioia Ryan Vallow Daybell, about the children's whereabouts and welfare. Lori and her new fifth husband, Chad Guy Daybell, claimed that J.J. was staying with family friend Melanie Gibb in Arizona, where they had lived before moving to Idaho in early September 2019, which Gibb later denied. Police efforts to locate J.J. led to the discovery that Tylee was also missing.

Complicating circumstances around the disappearances was a string of suspicious deaths. Lori's estranged 4th husband, Charles Vallow, was shot and killed in July 2019 by Lori's brother, Alexander Cox, who claimed self-defense; Cox died of a blood clot on December 12, 2019. In early October 2019, Brandon Boudreaux, the then-estranged husband of Lori's niece, Melani, was shot at in the driveway of his Gilbert, Arizona, home from a vehicle still registered to the deceased Charles Vallow. In October 2019, Chad's wife, Tammy Daybell, was attacked in her driveway by what she believed was someone shooting a defective paintball gun. A few weeks later, on October 19, she died in her sleep from what was initially recorded as "natural causes". No post-mortem or autopsy was initially performed. After Chad and Lori's marriage two weeks after Tammy's death, law enforcement became suspicious and exhumed Tammy's corpse for autopsy.

On October 9, 2019, Tammy reported on her Facebook profile and to police that she had been shot at, in her driveway, by a masked man with what she believed was a defective paintball marker. The county sheriff's office did not find the perpetrator. Ten days later, Tammy was found dead in her home, purportedly from natural causes. Chad claimed that she had retired the night before "with a terrible cough" and died in her sleep.

Cox (who changed his surname to Pastenes, the surname of his wife) died on December 12, 2019. His death was attributed to blood clots and high blood pressure.

On July 11, 2019, Charles Vallow was shot and killed in Chandler, Arizona by Lori's brother, Alex Cox, who claimed self-defense. Cox alleged that he went to confront Charles about abusing his sister, whereupon "Charles Vallow struck him in the head with the bat, so he went to get his gun." Police did not pursue the matter further. Both J.J. and Tylee had witnessed the incident; according to an unidentified son of Charles' from a previous marriage, Lori did not inform the family about the shooting and he learned about it from the news. Lori was indicted in June 2021 for conspiracy to murder Charles.

As of September 23, 2019, a doorbell video of J.J. playing with a friend is the last known video of him taken. His last confirmed sighting was at Rexburg's Kennedy Elementary School. On September 24, 2019, Lori contacted the school to tell them that she was withdrawing J.J. from classes, claiming she would be homeschooling him. Tylee was last seen September 8, 2019, at Yellowstone National Park with her brother J.J., her mother Lori, and her uncle Alex Cox, Lori's brother.

In October 2019, two Venmo payments were made from Tylee's account to her older half-brother, Colby Ryan. One payment was sent on October 10, with a message that read "we love you", and the second payment was sent on October 16, with a heart emoji. Colby has said he had not heard from Tylee since these texts. After text-messaging Tylee indicating he was worried, he received responses from Tylee's cell phone that indicated she was safe but too busy to talk. After repeated calls to Tylee went unanswered, Colby became more worried.

Chad and Lori were married in Hawaii on November 5, 2019, two weeks after the death of Chad's first wife, Tammy Daybell. There they told others that Tylee had died in 2017 and/or that Lori had no minor children. Back in Rexburg, on November 26, police visited Lori's townhouse at the request of J.J.'s grandmother, Kay Woodcock, to conduct a welfare check on J.J. Lori told police that J.J. was in Arizona with a family friend, Melanie Gibb. That night, a neighbor saw Lori and Alex Cox packing a truck outside her home. When police reached Gibb by phone, she told police that J.J. was not with her and had not been there for several months. When Rexburg police and the FBI arrived the next day to search the home, it was abandoned. Chad's home was also searched by investigators.

More than a week later, Gibb called police saying that both Lori and Chad had asked her to lie to police about J.J.'s whereabouts but she refused. Police efforts to locate J.J. led to the discovery that Tylee was also missing. From December 2019 to January 2020, Rexburg police, the Fremont County sheriff's office, and the FBI intensified the investigation into the disappearances of the two children, as well as the investigation into Tammy's death and the flight of Chad and Lori from Idaho. Evidence was collected, and Tammy's body was exhumed for autopsy. Colby and J.J.'s grandparents pleaded with the Daybells to return the children, with the latter offering a reward of $20,000. Investigators contended that "'Joshua and Tylee's lives are in danger.', [...] the children are not with Chad and Lori. [... Lori] knows where they are or what has happened to them, but she has 'completely refused to assist this investigation, [choosing instead to leave the state with her new husband].'"

Authorities soon turned their attention to a Rexburg storage locker rented by Lori in October 2019. Inside they discovered items belonging to or associated with Tylee and J.J., such as clothing, bikes, and photographs, all of which had been abandoned when Lori suddenly left Rexburg at the end of November 2019. Video footage shows her and her brother, Alex Cox, moving items in and out of the locker prior to her departure.

On December 5, 2018, Chad and Lori appeared together on the Preparing a People podcast episode "Time to Warrior Up". Chad later stayed at the Vallow residence in Arizona. By February 2019, according to Charles Vallow, Lori was informing him that "she no longer cared about him or J.J." and claimed that she was the reincarnated wife of LDS founder Joseph Smith, then vanished for 58 days. The same month, Charles filed for divorce, stating that his wife had "threaten[ed] to murder him", taken US$35,000 from their joint bank accounts, and stolen his truck. He filed for an order of protection against Lori at the advice of his attorney, citing a "genuine fear for his life".

In 2015, Chad claimed he heard a voice telling him to relocate to Rexburg, Idaho. He and Tammy moved there from Springville, Utah, that June.

Around 2015, Lori read Chad Daybell's Standing in Holy Places series of books, reportedly becoming "obsessed" with them. In 2016, the Vallow family moved back to Arizona. In the fall of 2018, Lori and her friend Melanie Gibb attended a "Preparing a People" event, where Lori was introduced to Chad for the first time. According to Gibb, by the end of the weekend, Chad told Lori the two had been married in seven previous lifetimes. The two soon began a private communication.

On February 24, 2006, Lori married Leland Anthony Vallow (August 17, 1956, Calcasieu, Louisiana – July 11, 2019, Chandler, Arizona), commonly known as Charles Vallow, in Las Vegas, Nevada. Vallow, a lifelong Catholic, became a member of the Church of Jesus Christ of Latter-day Saints (LDS), converting to his new wife's faith. Vallow had two sons from a previous marriage, Nicholas and Zachary Chase. In 2013, the couple adopted Vallow's grandnephew, Joshua Jaxon "J.J." Vallow (born 2012), and in late 2014, they moved to Kauai, Hawaii.

In 2001, Lori married Joseph Anthony Ryan Jr., who legally adopted Colby. The couple's biological daughter, Tylee, was born in 2002. Ryan filed for divorce on August 13, 2004, which was finalized on May 18, 2005. In 2007, Ryan was attacked by Lori's brother, Alexander Lamar "Alex" Cox, who claimed Ryan had been abusive to Lori and the children. Cox tasered Ryan and threatened to murder him. He pled guilty and was sentenced to 90 days in jail, which he served in Austin, Texas.

Tylee Ashlyn Ryan (September 24, 2002 – c. September 9, 2019) and Joshua Jaxon "J. J." Vallow (May 25, 2012 – c. September 23, 2019) were two American children from Chandler, Arizona, who disappeared in September 2019 and whose remains were found buried in shallow graves on June 9, 2020 in Rexburg, Idaho, in their stepfather Chad Daybell's backyard. Tylee was last seen alive at Yellowstone National Park on September 8, 2019. Her younger adopted brother, J.J., was last seen alive on September 23, 2019, at Rexburg's Kennedy Elementary School. He was initially reported missing by relatives concerned about not only the children—whom they had not heard from in weeks—but also several other suspicious incidents.

Lori Ryan Daybell, also referred to as Lori Vallow Daybell, was born Lori Norene Cox on June 26, 1973, in San Bernardino, California. In 1992, at the age of 19, she married high school boyfriend Nelson Yanes, but the marriage ended in divorce shortly afterwards. At age 22, she married 23-year-old William Lagioia in Travis County, Texas, on October 22, 1995. She and Lagioia had a son, Colby, in 1996 (who was later arrested on two counts of sexual assault in Arizona in 2022, charges that were later dropped without prejudice), before divorcing on February 25, 1998.

Chad Guy Daybell (born August 11, 1968, Provo, Utah) married Tamara "Tammy" Douglas (May 4, 1970 – October 19, 2019) in Manti, Utah, on March 9, 1990. He graduated from Brigham Young University (BYU) in 1992 with a B.A. in journalism, and worked as a cemetery sexton, or gravedigger, among other jobs. In 2004, Chad founded Spring Creek Book Company, which he used to self-publish his end times fiction and other religious books. His partner in this venture was a man identified in media only by the name Douglas, a graphic artist and manager. Chad and Tammy had five children: Garth, Emma, Seth, Leah, and Mark.