The punishment came after Melissa Huckaby, 29, reached a plea deal with prosecutors that took the death penalty and the possibility of parole off the table in the killing of 8-year-old Sandra Cantu of Tracy, whose body was found in a suitcase pulled from an irrigation pond.
Huckaby offered no motive for the 2009 killing as she addressed the girl's mother, Maria Chavez. The victim was a playmate of Huckaby's daughter.
"I still cannot understand why I did what I did. This is a question I will struggle with for the rest of my life," Huckaby said, her voice trembling.
She said Sandra "did not suffer, and I did not sexually molest her."
"I'm asking you, Maria, for your forgiveness," Huckaby said. "I can't imagine forgiving someone who harmed my daughter. I hope someday you can forgive me."
Authorities had provided few details about the killing until Monday, when Judge Linda Lofthus lifted a gag order.
Prosecutors released a summary of their investigation that showed the cause of Sandra's death was "homicidal asphyxiation." They believe she was drugged then smothered with a cloth soaked in rubbing alcohol.
Prosecutor Tom Testa said he believes two other drugging cases against Huckaby were "practice attempts" leading to Sandra's killing. Charges also were dropped in those cases as part of the plea deal.
The summary included a pathologist's report saying she was found with a piece of bloody cloth tied around her head.
She also had injuries to her external genitalia that were consistent with a bent, bloodstained rolling pin found inside a church where Huckaby had taught, according to the report.
The blood stain matched Sandra's blood.
The victim's body also contained alprazolam, a prescription sedative commonly used to treat anxiety. Prescription bottles of alprazolam were found in Huckaby's purse and home, prosecutors said.
Loftus later agreed to unseal search warrant affidavits and grand jury transcripts. The documents were not immediately made available, however, because the Cantu family was considering whether to appeal that ruling.
Several news organizations, including The Associated Press, had filed motions seeking to unseal the material.
Huckaby entered her surprise plea last month to first-degree murder with the special circumstance of kidnapping. All other charges, including allegations that she sexually abused the girl, were dropped as part of the plea deal.
Sandra's family asked the court to play a video depicting her short life. The footage brought many in the courtroom to tears, including Huckaby.
"She changed the lives of a lot of people. A lot of people," said Daniel Cantu, Sandra's father, who broke down as he addressed Huckaby.
"All I can say right now is, repent and think about what you've done," he said.
Sandra's aunt Angie Chavez told Judge Linda Lofthus that Huckaby robbed her family of the ability to see Sandra grow up, go to college, fall in love, get married and have children.
"No amount of explanation can make any sense of what she did or why she did it." Angie Chavez said. "The only solace we have as a family is to know that she will never do this again."
Sandra was last seen on a surveillance video walking through the Orchard Estates Mobile Home Park on March 29, 2009. Prosecutors said Monday the girl can be seen looking in the direction of Huckaby's home before she goes off-camera.
Eight minutes later, the tape shows Huckaby driving her SUV from the mobile home park in the direction of her grandfather's church, where the bloody rolling pin was found.
A massive search ended April 6, 2009, when her body was found stuffed in a black suitcase pulled from the pond a few miles from the community where she lived.
A couple later told authorities that they saw Huckaby and her SUV at the pond on the day of Sandra's disappearance, and the woman told the couple that she was there to urinate.
Huckaby was arrested less than a week later after telling a reporter the suitcase belonged to her but had been stolen from her driveway the day Sandra disappeared.
Huckaby showed authorities a note that she claimed she found at the mobile home park that read, "Cantu locked in stolin suitcase thrown in water onn Bacchetti Rd. & Whitehall Rd witness."
The handwriting on the note was similar to Huckaby's, prosecutors said.
