The man who murdered college student Ellen Higginbottom has been sentenced to more than 30 years in jail.
Judge David Stockdale QC described the sexually-motivated, premeditated attack as "frankly chilling" as well as "savage and brutal".
Manchester Crown Court heard 52-year-old Buckley, from New Hall Lane in Preston, inflicted terrible wounds to the 18-year-old's neck and wrist with a knife.
There were also signs that she had been strangled and her clothing had been disturbed, although there was no clear evidence of sexual assault.
Shaven-headed Buckley showed little emotion during the hearing.
Judge Stockdale gave him life imprisonment and said he must serve 30 years and 280 days before he can apply for parole.
He also paid tribute to Ellen's parents, relatives and boyfriend Ryan Warren for how they have handled the ordeal.
At around 7.20pm on Friday, June 16, police received a call to report 18-year-old Ellen, from Worsley, missing from home.
Ellen had not returned from Winstanley College, this was extremely out of character and her family and friends were very worried.
A police search began in Orrell Water Park in Wigan, as this was the last place she was known to have been. Around 2.30am on Saturday Ellen’s body was sadly found.
Sentencing Buckley, Judge Stockdale said: “The facts, in my judgement, are frankly chilling. You subjected her to a savage and brutal attack.
“It was as cowardly and callous as it was brutal. She would have had no idea that the assault was coming, she will have been caught completely off her guard.
“What must have been going through her mind during her ordeal is beyond imagining.
“You went equipped and you targeted a lone female out of sight of other members of the public. You inflicted many wounds on her in a sustained and violent attack. She was taking an innocent walk, and you attacked her and you killed her.
“You have blighted forever the lives of many others. Ellen was studying for her A-levels with her entire adult life ahead of her. I wish to pay tribute to the patience, composure and forebearance Ellen’s parents, relatives and boyfriend have shown throughout this.”
Ellen’s mum Kay was too ill to attend court as she is currently battling a brain tumour and her father Michael was looking after her.
However, her boyfriend and his father were there and Ellen’s uncle and aunt watched proceedings on video link.
The court also heard about Ellen’s all-too-short life, with references to her passion for animals, her ambition to become a vet and her strong relationship with Mr Warren which had included the teenage couple making plans to spend their future together.
Prosecuting, Peter Wright QC told the court how CCTV revealed Buckley changed his clothes several times during the day of the murder, at one point discarding his trousers and boots in an Orrell garden.
He had been around the water park carrying a bag containing a blade, belt and rope as well as items of a sexual nature since dawn on June 16, speaking to several female dog walkers or pedestrians.
The court heard that following the attack he returned under cover of darkness with a spade but was scared away from the scene by the police helicopter searching for Ellen.
Soon after her body was discovered lying face down on the edge of a wheat field. Her clothes had been pulled up around her neck and down to her ankles, though there is no clear evidence she had actually been sexually assaulted.
Disturbances in the wheat field also showed her body had been dragged to the spot, probably from one gap in the surrounding hedge to another.
Fibres of the blue rope in Buckley’s bag were found on her shoes, suggesting he may have tied her ankles. The belt had been used to tie some of her clothing, leading the prosecution to say he had used it to bring her to the spot.
Defending, Michael Hayton QC said Buckley expressed remorse and regret for what he had done, though could offer no clear explanation for his actions.
The court heard Buckley had experienced losing his job and a relationship break-up but Mr Hayton stressed none of this could offer any justification or excuse for his behaviour.
Mr Hayton described the murder as a crime of “exceptional wickedness” and said Buckley had to come to terms with what he had done.
Judge Stockdale imposed a minimum sentence of 30 years and 280 days, taking into account the amount of time he has already spent in custody.
The judge stressed that is only the first chance Buckley will have to apply to the parole board, and gives no guarantee he will be released.
Detective Superintendent Howard Millington, of GMP’s Serious Crime division, said: “My thoughts will always be with Ellen’s family and friends, this was an absolutely devastating murder by a stranger of an innocent young girl with her whole life ahead of her.
“Buckley callously killed Ellen in broad daylight. He attacked her in the most brutal way as she was walking around Orrell Water Park before going to meet her friends who were taking their exams.
“I am glad Buckley will now be spending many years behind bars to contemplate the young life that he has stolen away, but I wish that we hadn’t even had to investigate this crime.
“I wish it hadn’t happened and Ellen was here celebrating her A-Level results with her friends and planning her future.
“I would like to pay tribute to Ellen’s family and boyfriend for the dignified way they have conducted themselves in what has been the most awful of times; we can never bring Ellen back but I hope they can gain some comfort in the fact that justice has been done.”
Ellen’s dad Mike Higginbottom said in a statement: “There can never be anything even remotely approaching justice for what was done to Ellen, but what can be done has been done and both Kay and I want to say a heartfelt thank you to everyone who has been involved in bringing about today’s achievement.
“We were tremendously lucky to have shared eighteen years with her and everyone else who knew her will identify with that feeling. She made the world a better place with pretty much everything she said and everything she did.
“We all would have liked more though, and we would especially have liked for her to have had more. For her to have seen the results of all her hard work, for her to have seen her friends fly the nest as they went all to uni, for her to have explored the world that she was just growing into.
“To have all that taken away from her in such a pointless and idiotic fashion fills us with an anger and resentment that does not represent who we want to be. But we wrestle it under control and learn to be better at being people. Because that’s what adults do.
“So if there’s anyone else out there thinking of doing anything even half this stupid, just take one piece of advice. Grow up.”
Following the sentencing hearing, David Graham from the CPS said: “Mark Buckley has been sentenced to life imprisonment today for the brutal murder of Ellen Higginbottom. This was a terrible crime which shocked the local community and has had a devastating impact on Ellen's family and friends.
"Mark Buckley went out that day equipped with a knife to carry out a violent assault. It was the prosecution case that it was a sexually-motivated and premeditated murder, and that he spent a number of hours that morning looking for a lone female to attack. We believe he selected his victim at random, and Ellen Higginbottom was simply walking through the park at the time he chose to attack, with tragic consequences.
"I hope today's sentence brings some sense of justice for Ellen's family and her many friends. Our thoughts and sympathies are very much with them at this very difficult time. We would like in particular like to acknowledge the strength and resilience shown throughout by Ellen’s parents, Michael and Kay, and Ellen’s partner Ryan."