Two 14-year-old boys have pleaded not guilty to the murder of 14-year-old Anastasia Kriégel in Lucan almost a year ago.
A jury has been sworn in at the Central Criminal Court to try the two boys, who cannot be identified because of their age.
One of the boys has also pleaded not guilty to the aggravated sexual assault of Miss Kriégel.
The trial is expected to hear from almost 150 witnesses and last around six weeks.
Earlier this afternoon, when the jury was being selected, Mr Justice Paul McDermott told the potential jurors that both young men were accused of the murder of Anastasia, known as Ana, at a derelict premises - Glenwood House, Laraghcon, Lucan, in Co Dublin - 3km from her home.
They were told her naked body was discovered on 17 May 2018, three days after she went missing.
The judge told the jury panel that the case had been the subject of media attention and they may have heard certain things in the media.
He told them that if there was any element they felt would prevent them being able to give an independent judgment on the case they should bring it to his attention.
Mr Justice McDermott said they should not serve if they had a firm or settled view that either of the accused was guilty.
The judge told them the details of the events would be upsetting and he warned them about the nature of the evidence.
He said the fact these events involved young people could make it more upsetting than other cases of this kind.
Mr Justice McDermott said very serious offences were alleged against the two boys and the nature of the evidence was likely to cause upset.
The judge read out a list of almost 150 witnesses who are due to give evidence in this trial.
He warned the potential jurors that the accused were entitled as children to have their identity protected and warned that it was an offence to disclose their identities or any identifying details to anyone.
Each boy stood as the charges were put to them before the jury panel.
Boy A pleaded not guilty to murder and to sexually assaulting Anastasia Kriégel in a manner that involved serious violence to her.
Boy B pleaded not guilty to murder.
The case will resume tomorrow morning.