One of the boys accused of the murder of 14-year-old Anastasia Kriégel in Lucan almost a year ago was carrying a backpack, containing gloves, knee pads, shin guards and a homemade, "zombie-type" mask, the Central Criminal Court has been told.
Two 14-year-old boys have pleaded not guilty to her murder and one has also pleaded not guilty to violently sexually assaulting her.
The jurors were told the prosecution case is that Ana was dead within 40 to 45 minutes of leaving her home on 14 May, 2018.
Ana Kriégel was last seen at her home at around 5pm on the evening of 14 May, prosecuting counsel, Brendan Grehan, told the jury.
One of the accused boys in the case called to her home, he said, and told her the other boy - Boy A - wanted to meet her in the park.
When Ana’s mother came home, she tried to contact her daughter on her phone, but got no answer. She set off to try to find her at around 5.40pm or 5.45pm, but Mr Grehan said the prosecution case was that, by that stage, Ana was already dead.
He said the two boys gave differing accounts of what had happened. There were divergences between their stories and between what they had said themselves on different occasions.
There was CCTV footage of Ana with Boy B heading to the park the jurors were told. Mr Grehan said Boy A was seen not long after 5.30pm that evening, limping, with blood on his face and clothes.
He told his friend, his parents and gardaí that he had been attacked by two men but had managed to fight them off.
But Mr Grehan said that story was made up and the prosecution case was that he had received his injuries while in a struggle with Anastasia, during which he sexually assaulted and killed her.
Gardaí found the teenager's body at around 1pm on 17 May. She was in a small room in a derelict farmhouse - Glenwood House - in St Catherine’s Park, in Lucan.
Her body was naked, except for socks on her feet. There was a ligature around her neck made from very distinctive builder’s tape.
Mr Grehan said Ana had obvious head injuries and the scene was bloody. Her damaged clothes were scattered around the room. And her broken phone was also found in the room.
He told the jurors the post-mortem revealed severe and extensive injuries to Ana’s head and neck, as well as additional injuries suggesting sexual assault.
He said the conclusion was that she had been violently assaulted within the room and that there had been a struggle.
Mr Grehan said the case against Boy A relied on the lies the prosecution say he told, as well as compelling, coercive objective forensic evidence. Mr Grehan said Boy A was connected to the scene by male DNA found on Ana's neck, and the tape around her neck, along with semen found on her top.
He also told the jury various items from Boy A's home connected him to the murder. He said these included the contents of a distinctive backpack he was seen carrying in the park - gloves, knee pads, shin guards and "most chillingly" a homemade "zombie-type" mask. He said there was no explanation consistent with innocence to explain the objective, scientific facts.
In relation to Boy B, Mr Grehan said the prosecution case was that he helped with the murder of Anastasia Kriégel, knowing what was going to happen. He lured her from her home knowing she was interested in the first boy, and "handed her over" to Boy A, knowing preparations must have been made for what was going to happen.
Mr Grehan said Boy B provided the builder's tape for the ligature, remained and "voyeuristically" watched the murder and sexual assault, participated in the cover up afterwards and lied repeatedly to gardaí and others about what he saw, knew and did.
Mr Grehan said it was not credible to suggest Boy B did not know what was going to happen and the prosecution case was that he had been explicitly told of the intention to murder Miss Kriégel in advance.
He told the jurors the two boys were best friends and had "peculiar interests", which he was not going to go into at the moment.
Mr Grehan told the jurors that Anastasia Kriégel found her teenage years difficult. She was the object of bullying and engaged in a certain amount of attention-seeking behaviour.
She had been attending counselling on the day she disappeared. He said she was someone who craved friends and friendship and was "vulnerable" and an "easy mark" for someone who wished to take advantage of her.
Earlier, Mr Grehan told the jurors to keep at the forefront of their minds that two children were on trial accused of the murder of another child.
He warned them that they had to consider each charge against each boy individually. He also told them to bear in mind that a person who helps another person commit an offence, can also be guilty of the offence, even if they did not physically do it themselves.
Mr Grehan told them that what one accused person says about another accused person in their absence is not evidence against the other person.
The trial is expected to last six weeks.