When the second accused boy returned from St Catherine's Park at around 6pm on 14 May 2018, he finished his homework. Then he went to his room to continue watching his favourite animated series.
The first indication his parents had that anything was amiss, was when gardaí called to their home late that night, looking for information about a missing girl.

His mother called the boy to the door and gardaí asked him if he knew Ana Kriégel and when he had last seen her. 
Standing behind his mother, the boy gave the first of many different versions of what had happened that afternoon.  He said he'd called to Ana's house at 5pm that day. 

They had gone to St Catherine's Park, spoken briefly there and then turned back in different directions.  He said he'd last seen her at 5.40pm and told gardaí he didn't know her very well.
He didn't mention his friend, and co-accused at all until he spoke to gardaí again the next day.  This time he claimed he had been asked by Boy A to call for Ana and bring her to the park so the other boy could tell her he wasn't interested in her. 

Gardaí brought both boys to the park to take them through the route they said they had walked with Ana.

The gardaí grew concerned when they saw "a look" between Boy A to Boy B after the second boy described stopping at a certain point and going no further.

Sergeant Aonghus Hussey gave evidence that when he saw this look, he felt immediately there was something wrong. Statements were sought from both boys to clarify the issue. 

Sergeant Aonghus Hussey

Boy B said he had "no clue" what had happened to Ana. 

Read more:
Boy A and Boy B guilty of murdering Ana Kriégel
Evidence gave brief glimpse of Ana, a 'unique' girl 'full of fun'
The 'overwhelming' forensic case against Boy A
Two boys are guilty of murder - what happens next?
Watch: The route taken to Glenwood House

No forensic evidence was ever uncovered against Boy B linking him to the murder.  The case against him relied on what came out of his own mouth the jury was told, and they would have to consider where the lies ended and the truth began.
The prosecution case was that Boy B aided and abetted the murder: that he lured Ana from her home, knowing what was going to happen. 

Prosecuting counsel, Brendan Grehan said Boy B "handed Ana over" to Boy A, knowing preparations must have been made for what was to happen. 

He said the boy provided the builder's tape for the ligature around her neck, "voyeuristically" watched her murder and sexual assault and lied repeatedly about what he saw, knew and did. 

"He was present when she was brought to the ground," he told the jurors, "he was present when she was strangled and stripped."
CCTV footage from the evening of 14 May 2018 showed Ana walking behind Boy B as they walked through St Catherine's park. They were seen crossing a field near the BMX track, in the direction of Glenwood house just before 4.45pm. 

Thirty five minutes later, Boy B could be seen walking back in the opposite direction, on his own. 
Boy B was arrested by appointment at Finglas Garda Station on 24 May 2018.  As in the case of Boy A, special arrangements were made at the station because of his age.  It was arranged that no other prisoners would be brought to the station that day. He was not put in a cell - instead a separate, large room was set up to be used by the boy, his mother and his solicitor for consultations and for rest. 
Normally interviews with suspects are not played in court. Instead, the memorandums of interviews are read and confirmed by one of the interviewing gardaí.  One reason for this, is that the recorded interviews are often extremely tedious. One garda asks questions while the other laboriously writes down each answer, meaning the pace tends to be very slow and stilted. 
In the case of Boy B however, a decision was taken to allow the jurors to watch his demeanour and trace the evolution of his many stories. Mr Grehan said he knew it was an imposition, but he hoped, having seen the interviews, that the jurors would understand why this was considered proper and appropriate. 
Mr Grehan told the jurors the interviews showed a boy who was "highly intelligent, highly articulate, highly composed".  He suggested the boy was not in the least bit intimidated by surroundings that would "bring most people to their knees".  

This was surprising, he said, but did not equate with guilt – some people were more composed than others.
The eight men and four women on the jury, could not take their eyes off the screens as Boy B spoke. Even during breaks in the interviews, when no questions were being asked, everyone remained transfixed by the screens situated around the courtroom, as the boy on the videos, stretched, yawned, folded and unfolded his arms or fiddled with his shoe. 

His solicitor sat to one side of him, his mother to the other.  
Playing the interviews, meant jurors also got the chance to hear the boy's tone of voice and the manner in which he answered questions, something usually very difficult to discern from memos read at break-neck speed by barristers. 
In the first interview, the boy pointed out all the relevant locations "for the story" and he gave his version of what had happened.  In what became a familiar pattern, he told gardaí that this version was the truth before going on to change his account.
The two interviewing gardai, Detective Garda Donal Daly and Detective Inspector Damien Gannon, told the boy that there were CCTV cameras in St Catherine's Park and that hours of footage had been gone through as part of the investigation. They asked the boy if he was satisfied that he had told them the truth.

Boy B said "one or two parts" of what he had said might be wrong.  After spending some time thinking, he said he may have walked further with Boy A and Ana than he had initially said.  He pointed out another location to gardaí as the place where he had left the group. 

"That's it, that’s definitely it" he said. 
Mr Grehan said the boy was "gauging all the time" if the gardaí had evidence that could put him closer to the abandoned house where Ana's body was found. 

Garda Daly and Inspector Gannon showed incredible restraint, Mr Grehan told the jury.  Far from interrogating the then 13-year-old boy, they questioned him, persevered, pleaded with him and implored him to tell the truth.
In his fourth interview on 25 May,  the boy admitted telling gardaí "a lie" and a "fake story" and told them they probably wanted an explanation as to why he lied.

But Mr Grehan said, the boy lied again after explaining to gardaí that the reason he failed to tell the truth in the first place was because he was scared and nervous.  
Gardaí increased the pressure in his final interview, on the same day, telling the boy to stop trying to make his story meet the facts, and to tell them the truth. For the first time, the boy admitted being near the house but insisted he hadn’t gone in.

He described hearing a scream and running away. He thought Ana and the other boy "got attacked or something". He cried as he said he was scared but thought his friend would be able to handle the situation.  
After leaving the interview room with his mother and his solicitor for almost half an hour, he came back and went on to give two further versions of what happened, ultimately admitting that he had been in the house, and that he had seen Boy A flip Ana to the ground, choke her and begin to strip her.

He told the gardaí "it looked horrifying" and at their request, drew a sketch of what he had seen.
It took two-and-a-half days, to play the ten hours of interviews from Boy B's first arrest on suspicion of murder to the court.  But when jurors returned to court after lunch on 23 May, to watch further interviews, they were told the trial was not in a position to proceed that day. 
The boy's Senior Counsel, Damien Colgan had told the judge that his client had suffered a panic attack at lunchtime.  An ambulance was called to the criminal courts, and paramedics examined him, although he was not taken to hospital.
A decision was taken by Mr Justice Paul McDermott to shorten the hours the court would sit, in an effort to avoid a repeat of the episode.  Asked by the judge what he should tell the jury about what was going on, Mr Colgan said he would rather nothing was said about a "panic attack".    
The judge said that if an adult was enduring such a trial, it would be an enormous strain -  for a 14-year-old, it was all the more difficult.  He said it was exceptional to have two children on trial for murder. And he would take whatever action he could to alleviate the pressures.
With new shorter sitting hours in place, the final interviews were shown.  

The boy said he had picked up a stick while he was in the house. But he said it was not the blood stained stick later found near Ana's body. 

He admitted that the other boy had been wearing his home-made zombie mask during "the whole incident", something he had not mentioned before. And he said Boy A had told him a month before 14 May 2018, that he was planning to kill Ana. He said he had replied "in your dreams", and did not think his friend was being serious.
He denied seeing any blood, despite the fact that the top he had admitted seeing Boy A removing from Ana was later discovered to have her blood on it. 

He said he hadn’t told anyone what had happened, because he was ashamed of not helping, and was scared, shocked and horrified.
Asked why he hadn’t done anything about seeing his friend attack a girl he knew, he responded at first that he knew Ana "but wasn’t friends with her." 

When it was put to him that this was no justification for failing to help her, he said he realised he should have helped and that the gardaí didn't know how many times his dad had told him that. 

Gardaí said they did not believe what he was telling them, and that he was still lying.  The boy insisted he had told them the truth. 
The jurors were told that although the boy described Ana begging "no, no please don't do this", and crying, he did not give an account of Ana fighting back.

Mr Grehan said this did not fit with Ana's "battered, bruised, bloodied, broken-nailed body" which was damaged "tooth and nail."
Boy B said he had given Boy A a roll of the highly adhesive construction tape found around Ana's neck, a few weeks before this incident. Shown a picture of the tape at the scene in one of his interviews, he replied "Wait a minute, Holy Shit! Oh my god!"  

Mr Grehan suggested to the jury there was some "acting out" going on in the interviews as well as lying.  The prosecution described the tape as one of several "curiosities" in the case. The doctor who pronounced Ana dead said it was possible it was used to drag her by the neck from one part of the room to another. 
Over eight interviews over two arrests, the boy told lies about what he knew or saw, repeated them and persisted in them until gardaí managed to get him to reveal more.

Mr Justice McDermott later described the interview process as "an inch by inch, progressive peeling away of the lies".
In his closing speech to the jury, Mr Colgan said people lied for many reasons - he suggested the boy was traumatised, that he was in fear of Boy A and that he had been set up by the other boy.  While gardaí had described him as bright and articulate, Mr Colgan said the boy’s father called him naive and immature.  
Mr Colgan said the prosecution couldn’t point to any time or place where Boy A and Boy B had a conversation about what was to be done.  He said there was nothing to suggest Boy B knew what was going to be done to Ana and he believed Boy A wanted to talk to her about relationships. Mr Colgan said the interviews did not prove he knew what was going to happen.
But the prosecution said the boy had told deeply deceptive, devious lies, which kept changing.  Mr Grehan said when you considered all Boy B’s "truths", half truths and lies, it was unbelievable to suggest that Boy B didn’t know what the other boy was going to do.

He told them they could safely convict him of murder. 

Mr Justice McDermott warned the jurors that to rely on these lies, the prosecution had to establish that the motivation for telling them was the realisation of guilt. He said to convict Boy B, the jury had to be satisfied beyond reasonable doubt that he knew of the other boy's intention to kill and that he participated in the murder.  
The jurors were clearly persuaded by the prosecution case, and by more than 16 hours of watching the boy's own words.