A girl who saw Ana Kriegel in a park with one of the boys accused of her murder saw them "laughing and talking" and "they seemed to be having a good time", a trial has heard.
The girl gave evidence to the Central Criminal Court that she was out walking her dog when she saw Ana with Boy B, both of whom she knew.
She said the two were "having a brisk walk", were "laughing and jumping" and seemed to be having a good time.
In cross-examination, the teenager described it as a "sort of skip run".
"Ana seemed happy. She was laughing along with Boy B," she said. "They did a sort of a skip run, like the kind you'd do with your friend."
The teenager said she was too far away from Ana and Boy B to talk to them and she did not think they noticed her.
A second witness gave evidence that he was out walking his dog in the park when he saw Boy A. He estimated the time as 5.44pm. He said he spotted a young lad from a distance, who appeared to be "walking with a funny gait".
When the boy got closer he realised it was Boy A, who he knew. He said Boy A "looked like he'd been hit or something".
The witness said he was concerned for Boy A, possibly that he had been attacked. He asked him if he was OK, and he said he was.
Boy A "looked in rough shape", he said, and there appeared to be something that could be blood on his T-shirt.
The witness said Boy A told him that he fell and "just hit himself". Boy A also seemed "embarrassed" and the witness felt that he may have been bullied and just wanted to go home. Another juvenile witness said he was friends with Boy A and Boy B. On the day Ana disappeared he answered the door to Boy A. It was just before 6pm, he said.
"He was limping and holding his chest. He had his arm up to his chest," the youth said.
He gave evidence that he noticed blood on Boy A's T-shirt.
"Boy A looked scared," he said. He asked Boy A what had happened and Boy A told him he had been attacked by two older teenagers in the park.
The trial also heard how a schoolboy was seen heading across a field toward a disused farmhouse where Ana's body was later found, on the evening she disappeared.
Gerard Redmond told the court that he was walking home with his dog through the park. It was 5.07 or 5.08pm, he said.
He observed a schoolboy walking in front of him. He was wearing a backpack and was walking along the top of a low embankment.
Mr Redmond said the boy suddenly "dropped down into the ditch and came up the far side into a large field that surrounds a disused farmhouse".
He said he noticed that the boy walked at a 45-degree angle to the road and made "a bee-line toward the disused farmhouse".
The youths, aged 13 at the time, have pleaded not guilty to the murder of Ana (14) at Glenwood House, Laraghcon, Clonee Road, Lucan, on May 14 last year.
One of the boys, Boy A, has also denied a charge of aggravated sexual assault.
The trial continues.