Even as she pleaded for a sentence that would let her live in sunshine again, a 17-year-old girl convicted of murdering her parents expressed little remorse other than admitting to mistakes.

Cynthia Alvarez said she had been a victim of abuse at the hands of her mother and stepfather, allegations disputed by prosecutors and family and friends of the deceased.

"Live life in my shoes," Alvarez told a Compton courtroom Friday. "If it was your child being raped, I bet you'd say, 'To hell with the law.' "

Los Angeles County Superior Court Judge Ricardo R. Ocampo, however, found that the October 2011 slayings committed by Alvarez and her boyfriend, Giovanni Gallardo, 18, were vicious and sophisticated attacks. Saying that he still hadn't seen remorse, Ocampo ruled that the maximum sentences of life in prison should be imposed.

Alvarez would be eligible for parole after 51 years. Gallardo would not be eligible because of a law mandating tougher sentences for people older than 16 convicted of murder. A recent state law, however, allows for a sentence reduction after 15 years served.

The teenagers, troubled by learning disabilities, latched onto each other at a Compton high school in 2010.

The boy complained of peers bullying him. The girl accused her mother of verbal and physical abuse, and her stepfather of sexual abuse. She later said that Gallardo threatened her too, but she was too scared to tell anyone. The boy didn't like that her parents disapproved of the teenagers' relationship.

Shortly before Halloween 2011, the bound and decomposing bodies of the girl's parents were found partially covered by cloth in shallow graves. In separate trials, jurors convicted both teenagers, who were tried as adults.

Gallardo was convicted of strangling Alvarez's mother, Gloria Villalta, 58, and beating her stepfather, Jose Lara, 51, with a baseball bat and stabbing him several times with a kitchen knife. Prosecutors alleged that the attacks were part of a planned ambush.

Alvarez told jurors that they left her mother's body in a car for several days after it didn't fit into a grave with Lara. Then they drove the car to shop for Halloween supplies for a party in the same home where the murders occurred. They traded in the victims' jewelry and car parts for cash.

Psychologists hired by the teenagers' public defenders testified Friday that the two have already begun realizing the gravity of their actions and that prison could be dangerous given their learning difficulties.

Alvarez's psychologist said the teenager suffered from a type of post-traumatic stress disorder because of the alleged abuse, believing in a fantasy that life would be great without her parents, and that the two teenagers could support themselves.

Deborah S. Miora, a psychologist for Gallardo, said he was a "follower in most ways" who is "borderline mentally retarded." She said Gallardo had dreamed of being an auto mechanic, something he could have achieved through rote learning in a structured environment.

"There is an individual in there, not a cold, callous person," Miora said.

During Friday's hearing, Alvarez barely budged in her seat. She bowed her head for much of the daylong hearing, shedding tears when others spoke of her alleged abuse.

Alvarez, reading from a written statement, told the court that she was scared of "doing life."

"I just need to remember my past is my past," she said.

A niece of the stepfather and the stepfather's sister, speaking to the judge, denied the abuse allegations. In a fiery speech delivered in Spanish, the sister, Ruth Lara, said Alvarez had proved to be bad and unnoble.

"It's sad that she planned this killing of people who wanted to stop her from getting into bad company like this guy," Lara said, gesturing toward Gallardo with a hand holding a moist tissue.

Gallardo did not speak, but his parents did. His father, Jorge, said his son has been "sick" for a long time. His mother, Alicia, told the judge that as she gave the teenagers a ride in a car days after the murders, she overheard Alvarez telling her son to incriminate himself.

"I know, as a mom, he didn't do it," she said.

paresh.dave@latimes.com

Times staff writer Jack Leonard contributed to this report.