The 15-year-old boy who murdered schoolgirl Ana Kriegel after sexually assaulting her near Dublin nearly 18 months ago has been jailed for life.

Ana, 14, was found dead in an abandoned farmhouse in May 2018 and two boys were found guilty of her 'sadistic' murder earlier this year.

Boy A, who was also convicted of aggravated sexual assault, was sentenced to life in prison today with a review period after 12 years.

The second boy, who is also aged 15, was sentenced to 15 years' detention with a review after eight years.

The 15-year-old boy who murdered schoolgirl Ana Kriegel (pictured) after sexually assaulting her near Dublin nearly 18 months ago has been jailed for life

Sentencing the boys at Dublin's Central Criminal Court today, Justice Paul McDermott said the lives of Ana's relatives had been 'shattered in the most cruel circumstances'.

'A healthy 14 year-old girl, with her future before her and her short life should not be defined by how she died,' the judge said today.

'Her precious right to life entitled her to live it to full potential, with fun, imagination, dancing music, a lovely and loving child in loving family.

'She hoped for wider circle of friends, growing up with some difficulties along the way, but full of variety, of potential and aspirations.

'Her family are bereft, the joy and security of the Kriegel family shattered in the most cruel circumstances.'

Speaking at a press conference in Dublin after the sentencing, Ana's mother Geraldine thanked all those who had supported their family.

Victim: The body of 14-year-old Ana (pictured in a family photo) was found in an abandoned farmhouse in May 2018

'We would like to express our extreme gratitude to Mark O'Neill and his team and An Garda Siochana who have put everything they had into finding those responsible for Ana's murder, Siobhan McIntyre, our liaison officer, for holding the family up through all of this pain, the legal team, the jury and the judge, the media for being so understanding, the victim support unit, our family, our friends and our neighbours,' she said.

'And thank you to all of the wonderful people out there that supported us and kept us going.'

Ana's father Patric added that he finally had justice for his daughter.

'Justice has been served for Ana. The judge has decided on the sentence, and that duty lies with him alone. For our part we can only say that forever is not long enough,' he said.

'Please remember Ana and keep her in your hearts somewhere.'

Garda Superintendent John Gordon extended his sympathies to the Kriegel family and paid tribute to the dignity with which they conducted themselves during the trial.

Haunted: Patric and Geraldine Kriegel, the parents of murdered Ana Kriegel, speak to the media outside Dublin's Central Criminal Court

'This is a difficult and complex case and we would like to acknowledge the support and help of the community at this time, without their help we wouldn't be in the place that we are today,' he said.

The two boys are the youngest convicted murderers in the history of the Irish state and have been granted lifelong anonymity because of their age.

Both boys are currently in custody in Oberstown Detention Centre in north Dublin, and will remain there until they are 18.

During the sentencing, Mr McDermott added: 'The evidence given by Ana's mother set out to me and all who heard it, the deep joy brought to her and her father Patric, I listened to and read her evidence, and nothing could be added to the simple sad truth of what she told us, there is no solace for them in this process.

'Ana's murder has resulted in a lifelong sentence for them compounded by the manner of its occurrence.'

Speaking directly to both boys, Mr McDermott said: 'Boy A, you took Ana Kriegel's life and subjected her to a terrifying sexual and physical assault in doing so.

'Boy B, you actively participated in her killing.

'You will both have to carry the guilt and shame of your involvement and the devastation you wrought upon her family for the rest of your lives.

'Wild and wonderful': Mrs Kriegel paid an emotional tribute to her daughter Ana (pictured) ahead of the sentencing of her two 15-year-old killers

'Her family must bear their grief for the rest of your lives.

'When released you can reconstruct yours in a positive way, I hope you take it, and build towards that in your time in custody.

'A second chance you both so wrongfully denied Ana Kriegel.'

At an earlier hearing last month, Ana's mother Geraldine Kriegel gave an emotional impact statement in which she said she was haunted by her daughter's 'sadistic' death.

''No one could suspect the evil that lay in waiting for her. No one could anticipate the darkness that swirled in the souls of those that murdered and violated her,' she said.

'She wanted to live but she was not permitted to do that. Our lives are destroyed by what happened to Ana.

'We cannot look at a group of teenage boys in the same way ever again. That cold fear hits and brings all the horror back.

'Imagine the terror. Imagine the pain she suffered. That will live with us all our lives.

'We lie awake at night thinking about the fear she felt when she realised she was going to be killed.'

A post-mortem examination found Ana suffered head and neck injuries and there was evidence of sexual assault which was matched to Boy A's DNA.

Mrs Kriegel continued: 'We pace the house at night agonising about the torture she went through, the horrendous pain she suffered, the sadistic violation of her beautiful, pure and innocent body. '

'She was just a little girl with so many hopes and dreams and so much love inside her that she shared generously with all who knew her.

A 3D rendering of Glenwood House shown to the media by Gardai after the sentencing of two boys for the murder of schoolgirl Ana

'What words can describe how we feel at the loss of our wonderful girl.

'The pain of living without her is unbearable. There is such emptiness in our lives without her.

'Life without Ana is no longer a life, nor is it even an existence, it is a misery that we must endure for the rest of our lives.

'We have lost our precious daughter. Her brother has lost his sister and every family occasion is entrenched with pain and sorrow.'

On the first day of the murder trial Mrs Kriegel told the court that her daughter was very vulnerable and despite looking older than her 14 years, she was a 'child on the inside'.

The six-week trial heard how police officers found a book with a 'satanic pledge' at Boy A's home.

References included those to a 'satanist cult', detailing a number of 'rules', which included no 'talking about Jesus or God, only Satan'.

At the same hearing, the court heard that Boy A has accepted he caused the 14-year-old's death.

The teenager watched on at the earlier hearing as his grandfather said the boy was 'incredibly sorry' over Ana's death.

'[My grandson] is a loving, kind, caring child who was never in trouble or shown any aggression in my experience of him. He is loved by parents, sister and grandparents,' he said.