The man found guilty of abducting and murdering five-year-old April Jones in a sexually motivated attack must spend the rest of his life behind bars.
Mark Bridger, 47, of Ceinws, Powys, said he had accidentally run April over near her Machynlleth home and could not recall where he had put her body.
But the Mold Crown Court jury unanimously convicted him in a case lasting four-and-a-half weeks.
The judge branded him a Bridger 'liar, fantasist and killer'
Her remains have never been found.
Having deliberated for just over four hours, the jury returned three guilty verdicts - abduction, murder and attempting to pervert the course of justice.
Ever since his arrest, Bridger - only the 37th person to be given a whole-life tariff - stuck steadfastly to his story about not remembering where he put April's remains.
But shortly after he was convicted it emerged that while on remand at HMP Manchester, he told a prison priest he disposed of April's body in a river - thought to be the Dyfi close to where Bridger was arrested.
This conversation was the subject of legal arguments during the trial.
The jury was absent during the discussion and the Crown Prosecution Service decided not to submit the evidence.
What was revealed during the trial was fragments of bone consistent with a juvenile human skull were found among ashes in the woodburner, along with April's blood near to a number of knives, including one which was badly burned.
Bridger's cottage had also been extensively cleaned.
A library of child sex abuse images were found on his computer, and evidence of search terms including "naked young five-year-old girls" as well as pictures of murder victims including the Soham victims Holly Wells and Jessica Chapman.
He also had Facebook pictures of local young girls including April and her sisters.
Sentencing Bridger, Mr Justice John Griffith Williams said: "For the last four weeks, the court has listened to compelling evidence of your guilt, evidence which has also demonstrated that you are a pathological and glib liar.
"There is no doubt in my mind that you are a paedophile who has for some time harboured sexual and morbid fantasies about young girls, storing on your laptop not only images of pre-pubescent and pubescent girls but foul pornography of the gross sexual abuse of young children.
"What prompted you on Monday, 1 October to live out one of those fantasies is a matter for speculation but it may have been the combination of the ending of one sexual relationship and your drinking.
"Whatever, you set out to find a little girl to abuse. I am not sure you targeted April specifically... but you were on the prowl for a young girl."
Referring to the grief of April's parents, he added: "Without the knowledge of what happened to April, her parents will probably never come to terms with their grievous loss, described so eloquently in the impact statement.
"It is to be hoped, for their sake and for the sakes of all those who mourn April, that the verdicts will bring some measure of closure."
A statement read earlier in court on behalf of April's mother said she would never forget that night they allowed their daughter out to play with her friend, something they had done hundreds of times before.
"Words alone cannot describe how we are feeling or how we manage to function on a daily basis and I would never want any other family to go through what we are and will go through for the rest of our lives," it read.
"April was born prematurely weighing only 4lbs 2oz and was in intensive care for two weeks. She has always been a little fighter and we later found out that she had a hole in her heart and a heart murmur."
It went on: "As April's mother I will live with the guilt of letting her go out to play on the estate that night for the rest of my life.
"She fought to come into the world, she fought to stay in this world and he has taken her not only from us but from everyone who loved her.
"I will never see her smile again or hear her stomping around upstairs and on to the landing.
"We will never see her bring home her first boyfriend and Paul will never walk her down the aisle. How will we ever get over it?"
Outside the court, senior investigating officer Det Supt Andrew John said the strength of evidence against Bridger was overwhelming and he was responsible for the most horrific of crimes.
"Justice has been done and Mark Bridger, an evil and manipulative individual, will have his liberty taken off him," he said.
"He abducted and murdered April and has then gone to enormous lengths to destroy the evidence, conceal his involvement and avoid detection."
April's disappearance sparked the biggest missing person search in UK police history, focusing on around 650 areas near her home town and involving hundreds of experts as well as thousands of members of the public.
Dyfed-Powys Police received help from 45 other UK forces.
Insp Gareth Thomas who led the search told the jury he was "extremely confident" that if April's body was anywhere in the vicinity, it would have been found.
The seven-month search for her remains was finally called off last month.