(CNN) -- Admitted killer John Albert Gardner III bowed his head and wept at his sentencing Friday as the parents of his teen victims called him a monster and coward for raping and murdering their daughters.
At the end of the hourlong hearing, the convicted sex offender was sentenced by Judge David Danielsen to three consecutive terms of life without parole for murdering Chelsea King and Amber Dubois and attacking a jogger.
The case has sparked calls for tougher penalties against sex offenders.
Dressed in a green jailhouse jumpsuit, his gaze on the floor, Gardner became emotional as the parents took turns attempting to articulate the agony of their losses before a packed courtroom in San Diego Superior Court.
The themes of their statements alternated between celebrations of the teens' lives and expressions of rage directed at Gardner.
"Look at me," Kelly King, Chelsea's mother, tearfully demanded of her daughter's killer after taking the podium. She paused and waited as a red-faced Gardner slowly lifted his eyes, casting a quick glance at her before shutting them.
"What I feel is so much deeper than I ever dare to express in a public forum. There are things I'd like to say, but to protect my son and to maintain the dignity of my family, my words will be far too mild to adequately speak the disgusting truth about you," she said tearfully, trembling as she spoke.
"Chelsea was a sweet, loving and innocent soul who could not have fathomed the wretched piece of evil that ended her beautiful life on that day."
Gardner, 31, pleaded guilty April 16 to raping and murdering the San Diego-area teens in a deal with prosecutors that spared him the death penalty. He also pleaded guilty to assault with intent to commit rape of a jogger who managed to fight him off.
CNN does not name survivors of sexual assault.
The young woman also addressed Gardner in open court Friday.
"As a runner, I've always gloried in the peace that comes in the utter solitude of a long run," said the woman, who was attacked in December 2009. "In a single instance, this man took from me the safety and solitude of my own mind."
She said it was important for her to appear in court to represent the slain teens, despite the "pain and guilt" she feels as a survivor.
"I came here to stand today as a witness for Chelsea and Amber. I came to watch as justice is served for the horrifying acts he has committed," she said, fighting back tears. "I come here today for all the women who have ever been victims of violence, to ask with Chelsea and Amber's voices to remove this man from our world, to make us a little safer by locking him up permanently.
King was also running on a trail near the Rancho Bernardo Community Park on February 28 when Gardner attacked her and dragged her to a remote area, according to court documents. He raped and stabbed the 17-year-old and buried her body in a shallow grave. He was arrested three days later, after his DNA was matched to semen found on her clothes.
During the emotional hearing, Gardner was called an animal, monster and sociopath. King's father, Brent, said the most appropriate name for the registered sex offender was "coward."
"As I thought about what I would say to you today, I realized that names like 'monster and 'animal' in a perverse way let you off the hook. You knew what you were doing when you chose to wait for and corner Chelsea," King said.
"The most fitting name for you is 'coward.' You are not a man. You are just a weak, pathetic coward who preys on unsuspecting young girls half your size. You are evil not because of some sickness or disease, so don't blame anything or anyone for your crimes. You intentionally chose evil and now you have to live with that evil festering inside you and eating you up as you rot in a prison cell for the rest of your life."
Dubois, 14, was last seen alive walking to Escondido High School on February 13, 2009. She was considered a missing person for more than a year, until Gardner led authorities to her remains in March -- after his arrest in King's death -- in exchange for assurances that it would not be used against him in court.
Gardner admitted to raping and stabbing Dubois and burying her in a shallow grave in a remote area near Pala, according to court documents.
Without the plea deal, San Diego County District Attorney Bonnie Dumanis said last month, her office did not have enough evidence to charge Gardner in the death of Dubois.
After 15 months of wondering about her daughter, Dubois' mother said knowing her fate brought little closure.
To understand her grief, Carrie McGonigle said, you had to know Dubois for the loving and gentle-hearted person known to friends and family -- a bookish animal lover who chose Barnes and Noble over the mall.
"The day she was abducted her backpack was filled with valentines for her friends and joy in her heart because she was carrying a check to adopt a baby lamb for a school project. To appreciate the profound kindness and love that has been stolen from my life, you only need to understand how truly excited she was about the opportunity to nurture another living thing."
In addition to the victim impact statements, the King family also submitted a video of their daughter's friends describing the vivacious teen's gift for bringing intense passion to music, athletics and personal relationships.
"The thing I love most about Chelsea was the conviction and passion for everything she did and everyone she loved," one male friend said.
Not long after Gardner's arrest, King's parents vowed to push for tougher sentencing guidelines for violent sex offenders and more intensive monitoring of parolees.
California's "Chelsea's Law" calls for life imprisonment without the possibility of parole for any forcible sex crime against minors that includes one or more aggravating factors, including the victim's age or whether the victim was tied, bound or drugged.
The bill also would institute more intensive monitoring of parolees and lifelong GPS tracking in some cases.
Gardner's history with the state parole board also led Gov. Arnold Schwarzenegger to order a review of the system.
He was paroled on September 26, 2005, after serving five years for two counts of lewd and lascivious acts on a child under 14 and one count of false imprisonment for attacking a 13-year-old neighbor.
In September 2007, he incurred a parole violation when his parole agent found that the college he was living near had a day care center and he was asked to move. When it was determined that he had found compliant housing, he was discharged from parole and removed from GPS monitoring on September 26, 2008.
Speaking to the court, Dubois' father lamented that the justice system did not heed the warning of a doctor who recommended that Gardner receive as much prison time as possible before his incarceration in 2000.
" 'The defendant does not suffer from a psychotic disorder. He is simply a bad guy who is inordinately interested in young girls,' " Dubois said, quoting a report from psychiatrist Matthew Carroll, who evaluated Gardner.
"Again, I cannot help to ask on behalf of my family, who is at fault here? Is it this cold, heartless monster, is it the failures in the law enforcement systems or perhaps it is even us who have not forced and held accountable the people and the organizations who are supposed to protect us from these predators?"
Echoing statements he made at Gardner's plea hearing, Brent King said his family would have preferred the death penalty, but knew it was an "empty promise" in California.
The father also laid blame on the killer's mother for not ensuring that he was registered at her address, a condition of his parole, or notifying police of his residency when the girls went missing.
"Your mother, Cathy Osborne, knew what you were capable of and did nothing to protect us from you. She knew who you were after you violently beat and tried to rape that poor 13-year-old girl a decade ago," he said. "She harbored you, indulged you and put every child in our community at risk. ... Ms. Osborne, you have Chelsea's rape and murder and our pain on your soul."
Mary Duval, chief executive officer for the Sex Offender Solutions and Education Network, an advocacy group for registered sex offenders, said anger-induced legislation is not the answer.
"If the current reform efforts focus on punishing and restricting all former sex offenders instead of those who are the most dangerous, the goal of protecting children will once again be foiled due to anger, fear and misinformation ruling the day," she said. "The facts of the Chelsea King and Amber DuBois cases should be enough to persuade politicians and the families to look for better answers."