Kayleigh's mother, Sara Krueger, 23, and her boyfriend Ryan Scott Warner, 26 have been charged with murder and felony assault on a child, causing death. Neither charge includes special circumstances, ruling out the death penalty, for now.
District Attorney Gary Lieberstein told reporters that could change if Monday's autopsy reveals evidence of sexual assault.
"There is not evidence sufficient in that regard. If that changes then the avenue is open," Lieberstein said.
The police report revealed that Kayleigh was beaten to death and that after being arrested in El Cerrito, the couple admitted to stuffing the body in a suitcase and then a freezer for three days.
Napa County Child Welfare Services Director Linda Canan could not comment about the specifics of the case.
"We have a child who died. I don't know, everything I know at this point in time tells me that there was nothing done incorrectly. That doesn't mean the system didn't fail," Canan said.
ABC7 News spoke with a member of the Slusher family Tuesday morning. The woman said Kayleigh's death is the most horrible thing that could ever have happened, that they'd like to keep to themselves right now and they have not yet decided on the funeral arrangements.
The Napa County Coroner's Office has completed the autopsy on Kayleigh, but can't release the little girl's body to the Slusher family until the district attorney says it's OK. The coroner's report won't be available until late next week.
Kayleigh was found dead in her mother's apartment Saturday afternoon during a welfare check.
Krueger and Warner were arrested on Sunday at the El Cerrito BART station after being spotted by an alert citizen who notified police.
Kayleigh's biological dad is serving a 3-year sentence at San Quentin for reckless driving and evading police.
Krueger and Warner will return to court on February 25 with public defenders to enter their pleas.