Three dog walkers who were enjoying the facilities at St. Catherine's Park in Dublin the night Ana Kriegel disappeared gave evidence during the first week of the trial.
It would be easy to cover up these witnesses – in fact, none of them spent much time on the witness stand, nor questioned at any size – and found their evidence irrelevant.
However, his accounts, taken in conjunction with almost 700 hours of CCTV footage, were part of the meticulous construction of the suit against the two defendants by gardaí.
The first to stand on the witness stand was a girl walking her dog.
She knew Ana and Boy B and saw them walking diagonally across the soccer field.
They were "laughing and talking" and "they seemed to be having fun," she said.
The teenager said she was too far away from Ana and Boy B to talk to them and did not think they would notice her.
This account was equipped with images of CCTV, which despite nebulae, showed two people walking the soccer field at the specified time.
A second witness showed that he was walking with his dog in the park when he saw boy A.
He estimated the timetable only after 5:44 pm.
He was standing near the small parking lot when he saw a young man who seemed to be "walking with a funny walk".
When the boy got closer, he realized it was boy A, whom he knew.
He said that Boy A "seemed to have been hit," and there seemed to be something that could be blood on his T-shirt.
He said that Boy A said he fell and "hit himself."
Boy A also seemed "embarrassed" and the witness felt that he may have been bullied and just wanted to go home.
Although there was no CCTV footage of this encounter between the man and Boy A, the dog walker's bill and time fit in with other CCTV covers collected by the gardaí.
A second dog walker, Gerard Redmond, said he saw a student heading straight into the disused building where Anne's body was found later the night she was last seen.
Mr. Redmond said it was at 7:00 PM or 7:00 PM when he saw a boy in front of him.
He was wearing a backpack and was walking on top of a low embankment.
Redmond said the boy suddenly "fell into the ditch and climbed the other side into a large field surrounding an abandoned house."
Gardaí believed that this person was the boy A.
He also fitted with CCTV footage of a boy identified as Boy A by his co-accused in an area of the park known as Meadowfields around the same time.
That was "very strange," Boy B later said in interviews, before telling police about a shortcut that Boy A could have taken back to where he was. [Boy B] had said that he and Ana had known boy A.
Meanwhile, the father of boy A said that his son was shaking and very shaken the night that Ana disappeared and said that he had been attacked by two men.
His father wanted to report him to make sure it would not happen again and he and his son went for a walk to see if they could locate the two criminals.
He said they went to the park and Boy A pointed to the area where the "two boys jumped into it."
Boy A later showed Detective Garda Gabriel Newton, where he said he had been assaulted.
His father asked the park guard if he had seen anything and he had not seen anything.
In his evidence, Park Ranger Norman Macken said he noticed small pieces of blood on the fingers, face and pants of a teenager who told him he "hid a little" in the forest.
Macken said he talked to the boy after his father hit the ranger's station to complain that his son had been "jumped" in the woods by a "pair of big cats."
Macken said he asked the boy what had happened.
The boy put his hand to his eyes and said that he "just hid in the forest."
The boy's hands were shaking and Mr. Macken said he did not seem to want to get involved with him.
The day after Ana's disappearance, Gardaí and Boy B retrace the route he said he had made with Ana.
Boy B showed Sergeant John Dunne, where he claimed to have seen Ana for the last time.
He said that Ana went to one side and he and boy A went out in different directions.
That afternoon, boy A and boy B traveled the route for the second time with gardaí.
At one point, the boys took a right turn on a tree-lined path and Sgt Dunne asked Boy B if this was correct since he had gone to the left.
"Boy B stopped and said it was not over," said Sergeant Dunne.
"I watched Boy A take a look, a look at him."
Nothing was said, he added, and Boy A denied it.
However, this look was enough to raise the suspicions and they were worried about the inconsistencies in the accounts of the boys.
The discrepancies were confirmed when they assembled the CCTV images.
Gardai later gave proof of the time it would take to walk the three miles of Ana's house to Glenwood House.
Depending on the walking speed, it varied from 19 to 24 minutes.
These little pieces of evidence and CCTV footage helped prove three things.
This helped prove that boy B was lying during interviews with gardaí – as the route boy B claimed to have made did not coincide with what was captured by the cameras located in St Catherine's park.
Second, there were no CCTV footage or visual appearances of three people together in the park, casting doubt on Boy B's claim that he and Ana had met with Boy A in the park.
Thirdly, the CCTV footage cast doubt on Boy A's claim that he had been attacked in the park, as the alleged culprits, whom he described in detail to the police, were not captured in any camera.
Ultimately, these little evidences also helped to convict boy A and boy B of Anne's murder.