Lori Vallow and Chad Daybell are set to go on trial in 2021 to face conspiracy charges and several other felonies following the deaths of Vallow’s children, Tylee Ryan and Joshua “JJ” Vallow.

A new report from "48 Hours" on CBS with the transcript from Daybell’s August preliminary hearing revealed the disturbing scene investigators uncovered in his backyard when they discovered the children’s bodies.

In the transcripts from the hearing, Detective Rey Hermiosillo revealed he was one of the men who discovered JJ, 7, buried in a shallow grave in Daybell’s backyard.

“It was what appeared to be a small body tightly wrapped in black plastic, covered in duct tape,” Hermosillo said on the record.

Meanwhile, the second team of investigators searched the Daybell family’s pet cemetery. Although they initially dug up household pets, they came across a melted bucket that appeared to be out of place.

Hermosillo revealed they discovered Tylee’s remains at the pet gravesite. “Under the bucket was a partial human skull,” he explained.

However, because of the condition of Tylee’s body, it was difficult for investigators to determine her cause of death.

“The only thing we — we can know for sure is that … At one point, whoever did this, dismembered her body and burned it,” CBS News consultant Morgan Loew said.

While authorities do not have a clear idea of how the children were killed, they created a timeline around a photograph of Tylee, 16, and JJ on the last day of her life.

In the photo, Tylee could be seen holding JJ at Yellowstone National Park as Vallow’s brother, Alex Cox stood in the background. “That night, we know Alex was in his own apartment. And then … Police tracked his cell phone to Lori’s apartment at 2:45 in the morning on Sept. 9,” Loew stated.

“He’s there for a couple of hours. Then he goes back to his apartment, and then, after 9 in the morning, his cell phone appears … in Chad Daybell’s backyard.”

A few weeks later on Sept. 23, 2019, Cox returned to Daybell’s backyard, but that time he stayed on the property for about 17 minutes. Hermosillo revealed that JJ was found with duct tape wrapped around his body.

The detail made Loew question whether the child was buried alive. “Why do you bind somebody’s feet and hands and mouth in duct tape? You do it to keep them from — yelling or talking,” he said.

“The way they found that body leads you to believe that JJ was still alive … Because you don't go through all that trouble to somebody who’s already dead.”

Vallow and Daybell are both charged with conspiracy to commit destruction, alteration or concealment of evidence. If convicted of just those charges, Daybell could face up to 20 years in prison, and Vallow could receive a sentence up to 10 years in prison. No one has been charged in the murders of Tylee and JJ yet.

crime scene
This is a representational image showing a crime scene tape in Sunset Valley, Texas, on March 20, 2018. Getty Images/Scott Olson