Kayleigh was just three years old when police found her little body, partially frozen.

Trigger warning: This article details a case of child abuse and may be triggering for some readers.

On February 1, 2014, a friend called Napa Valley Police Department with concerns over three-year-old Kayleigh Slusher’s welfare.

When police arrived at the toddler’s home, they were greeted with a horrific sight: the body of little Kayleigh, lying on her bed.

She was partially frozen.

The friend later told police that he had visited Kayleigh's mother, 27-year-old Sarah Lynn Krueger and her boyfriend, Ryan Scott Warner, 29, the night before his 911 call.

He said he had found the little girl's body and told the couple to call the police. When they refused, he took it upon himself to call authorities.

Earlier this week, both Sarah and Ryan were found guilty of first-degree murder with the special circumstance of torture in relation to the three-year-old's death.

The pair were also found guilty of abuse of a child under eight causing death, and now face the possibility of spending the rest of their lives in prison without parole when they are sentenced in July.

Napa Valley Deputy District Attorney Kecia Lind told PEOPLE Magazine of the moment investigators found Kayleigh's body in the family home.

"She was in [the freezer] for at least a number of hours," says Lind.

"Her body was still extremely cold to the touch when the officers found her. We don't know for sure how long she was in the freezer."

Kayleigh was also found with a number of "horrific injuries", including 41 distinguishable injuries to her body.

"She had severe injuries and bruising to her head," Lind said.

"Essentially just all over her body... It was tough.

"The medical examiner described the amount of pain and suffering she would have been in during the time she was dying. It wasn't a quick process."

It's believed Kayleigh had been abused for at least a month or two before her death.

By the time Kayleigh's body was discovered by authorities, her mother and boyfriend had fled. Shortly afterwards, they were arrested after a woman spotted them dining at a restaurant.

Following her death, Kayleigh's father and other members of her family started a petition to protect other vulnerable children.

They are calling for a 'three strikes and you're out' system in regards to police being called to a home on suspicions of domestic violence, neglect or abuse of a child.

The petition - which reached over 6,100 supporters - argued that Napa Valley police had been called to the home of Kayleigh and her mother 14 times in the lead up to her death.

"They were called out to the home again 2 times just the week of her murder specifically for her safety and to do a welfare check," the petition reads.

"A few days later the media reported she died from blunt force trauma."