SURREY, B.C. -- A young man who was just days shy of his 18th birthday when he bludgeoned a 15-year-old girl to death in a suburban park near Vancouver was sentenced Friday as an adult to life in prison -- a punishment that prompted cheers in a crowded courtroom as a judge condemned the killer for devastating the young girl's family and leaving a community in fear.

The 21-year-old man pleaded guilty last year to killing Laura Szendrei in a park in Delta, south of Vancouver, in September 2010. Despite the adult sentence, which would typically allow the media to publish the offender's name, his lawyer indicated she plans to apply for a publication ban in the case.

Szendrei was beaten as she walked through a forested area of Delta's Mackie Park to meet a group of friends, who heard her screams and rushed to find her. The teen was beaten so severely she died the following morning in hospital.

The murder shocked the province, not just because of the age of the young victim, but also for where it happened: a popular public park on a sunny Saturday afternoon, with nearby sports fields teeming with people.

In the days that followed, Szendrei's parents made a tearful plea for help to catch their daughter's attacker as local residents wondered if their typically quiet bedroom suburb was safe.

The killer was arrested five months later after an undercover operation that ended with the man confessing and re-enacting the crime.

"I would give special emphasis to the devastation that the accused's actions have reaped on the family and friends of Laura Szendrei, which rings clearly and painfully from the victim impact materials," provincial court Judge Robin Baird said during Friday's sentencing.

"This offence has upset this community's sense of well-being and serenity. The accused has, doubtless, struck enduring fear into the heart of every Delta parent."

The offender was sentenced to life with no parole for at least seven years, though his parole eligibility will be reduced by the two years and eight months he has already spent in custody.

As the judge read his decision, describing Szendrei's killing in meticulous detail, the sobs of the girl's family and friends could be heard throughout the courtroom. When Baird announced he would be sentencing the man as an adult, those sounds were replaced with cheering and applause.

Outside court, Szendrei's family declared justice had been done. Her mother, Rachael, held out her hand in a peace sign and said, "Thank you, Judge Baird."

Mike Szendrei, the girl's father, said the judge had done "the right thing."

"It's for Laura," he said. "The rest of you parents out there, maybe you don't have to be scared that this guy is crawling around."

Szendrei's grandmother, Betty Rotaro, said the family has been waiting a long time for the killer to face justice.

"We can breathe again," she said, through tears. "We can try to put it behind us. At least we know that he got what he deserved."

The attack occurred on Sept. 25; the killer turned 18, when he would have no longer had the protections of the Youth Criminal Justice Act, on Oct. 1.

The offender listened from the prisoner's box, wearing a white dress shirt and his blond hair cropped short, mostly staring at the floor as the judge weighed his fate.

Before the judge imposed the sentence, the man stood and briefly addressed the court, saying: "I'm so sorry ... for all the pain I've caused everybody."

The court heard that the man left his house the day of the murder armed with a ligature fashioned out of plastic cable ties, a metal pipe, and a plan to find someone to rape. He had no particular victim in mind and he did not know Szendrei, who was merely the first person he encountered who was alone.

The court heard the man asked Szendrei to stop and help him fix his bike. He attempted to wrap the plastic strap around her neck, but when Szendrei screamed and ran, he hit her head several times with a metal pipe.

The young man quickly fled, but returned a short time later to gather the pipe and a hat that he had left behind.

By then, Szendrei's friends were crowded around her. The attacker told the group he had heard something and even volunteered to help look for Szendrei's attacker.

The man took steps to cover up his crime, but otherwise appeared to be unaffected. He went on a previously planned trip to Mexico shortly after to visit an uncle, and while he was there, he threw out the clothing he was wearing the day of the murder.

Before long, the police began to consider the man as a suspect. Investigators devised a Mr. Big-style undercover operation, in which the man was led to believe he had been hired by a video game development company.

When members of the fictitious video game company brought up the fact that the man was a suspect in a murder investigation, he admitted his involvement and asked for help evading police. He even re-enacted the killing at the scene of the crime.

Szendrei's murder was the culmination of a series of escalating attacks against women, all apparently motivated by the man's desire to violently rape someone. The court heard evidence that, earlier in 2010, he attacked three other women in another wilderness area in Delta.

In one instance, the attacker ran behind a woman and attempted to grab her buttocks. In another, he attempted to pull down a woman's pants while she was jogging in an attempt to grab or fondle her.

And in the third attack, he hit a woman with a stick "with an idea of disabling her" so he could either touch or have sex with her, the court was told.

The offender later told psychiatrists while in custody that he was driven by an anxiety around women due to his own lack of sexual experience. He claimed he only hit Szendrei to knock her unconscious in an attempt to ensure she wouldn't remember what happened, and he insisted he didn't think it would hurt or kill her.

The judge concluded the explanation was not believable and he described the man as a "sexually motivated murderer" who had not demonstrated any insight into what he had done.

The man's sentence is the maximum available to someone under 18 who is convicted of second-degree murder.

Had he been sentenced as a youth, he would have received a seven-year sentence, with the first four years served in custody and the remaining three possibly served in the community.

Delta Police Chief Jim Cessford said the murder shook the foundation of the community and was especially devastating for young people.

"We conducted an extensive investigation and I'm pleased we could bring the evidence and facts and the person responsible before the courts," Cessford said in a statement.