Mr Justice Jeremy Baker told the culprit, who cannot be identified for legal reasons and has subsequently been diagnosed as a paranoid schizophrenic, as he passed sentence at Wolverhampton Crown Court: “You carried out a brutal rape and murder with truly shocking violence."
“What took place in West Park in this city was not a matter of happy chance.
"It had been carefully planned by you to get Viktorija to meet you in isolation.
"You had planned to rape her and batter her to death with a weapon which was brought with you.
“Your mental illness may have been a contributory factor but did not significantly reduce your culpability.”
The victim, known as Tori, was mercilessly bludgeoned to death after being lured to a late night rendezvous at the wooden pavilion - nicknamed the 'black house' - in Wolverhampton’s West Park.
Blood staining showed she frantically tried to dodge a blitz of more than 20 blows that continued to rain down on her after she was clubbed to the ground on April 11 last year.
Many of the worst injuries were delivered with a hammer-like weapon that has not been found.
WATCH: Final images of Viktorija on CCTV
CCTV footage captured the final pictures of Viktorija alive.
The video shows Viktorija in Wolverhampton on the morning of April 11, shopping with friends in the city later in the day and on her way to West Park, where she was killed late that night.
Several of her teeth were found on the pavilion floor and she died within an hour from dreadful head injuries.
The semi naked victim was dragged around 150 metres and draped over a park bench where the body was discovered by a dog walker shortly before 7am the following morning. The gratuitous violence is believed to have started when she rejected his advances.
The defendant, aged 16 at the time, was determined to have sex with her and bombarded the Lithuanian-born girl with requests to meet in the park late at night after reviving social media contact following a break during which they lost touch.
WATCH: Mother and stepfather open up about death
In this video, Detective Inspector Caroline Corfield explains how the brutality of Viktorija's death shocked the police team investigating her murder.
Afterwards, Viktorija's mother and stepfather describe the awful moment they found out their 14-year-old daughter's body had been found.
He told Viktorija they would just 'chill out ' and smoke cannabis but the real motive for his renewed interest was revealed by his trawling of the internet before their meeting looking for information about the type of sex he inflicted on her.
Friends warned her not to go to the rendezvous but she ignored the advice and was last seen on CCTV heading for the park near her home in Mostyn Street, Whitmore Reans.
The jury unanimously convicted the defendant of murder after a trial at the same court in December and the case had been adjourned for pre sentence reports.
Viktorija's heartbroken mother Karolina Valantiniene said: "I hope nobody else on earth is as horrible as the defendant."
Her husband - Viktorija's step father - Saidas Valantinas added: "I feel nothing but anger towards him. I think people like him should be kept in isolation."
Police: Viktorija Sokolova's murder 'deeply distressing'
Detective Inspector Caroline Corfield, from the force’s homicide unit, said: “It was clear that the scene of Viktorija’s attack was a large wooden pavilion near to the boating lake, known locally as the ‘black house’.
"Her blood-stained baseball cap and earrings were found there and also, horrifically, three of her teeth which points to the violence of the attack.
"Her body had then been dragged to a bench some 150 metres away, where she was found.
“We also found footprints in Viktorija’s blood on the floor in the pavilion, the pattern of which were identified as those of Adidas Gazelle trainers, the same footwear later seen worn by the killer as he walked to and from the park."
DI Corfield continued: “The murder of Viktorija shocked the local community and the wider general public, not least because of the ages of those involved.
“As many young teens do, Viktorija was testing boundaries and could be wilful, but she was a popular girl and had the love and support of her family and friends. She certainly had her whole life ahead of her, but sadly that was brutally cut short.
“I am so proud of everyone who worked incredibly hard on this deeply distressing case. Nothing can compensate for the loss of Viktorija and her family have been put through an unimaginable ordeal. Our thoughts remain with them."