One of two boys accused of the murder of 14-year-old Ana Kriégel told gardaí he saw the other boy choking the schoolgirl as she lay on the ground.
The jury has watched Boy B's final interview with gardaí in May last year, after his arrest on suspicion of murder. Boy B was released from custody after this interview but was rearrested six weeks later on 7 July.
The jury will continue watching garda interviews conducted after the second arrest on Monday
Both boys deny murder. Boy A denies aggravated sexual assault.
In his fifth interview, gardaí again urged Boy B to tell them the truth about what happened on 14 May 2018.
In a previous interview, the boy had told them he liked a type of animation series, called animé.
Detective Garda Donal Daly told the then 13-year-old boy, this was not animé - it was real life and was "so, so important".
Boy B then told the gardaí that he had walked into the abandoned house in Lucan where Ana's body was found. He said he walked around, picked up a white board, put it down again and walked out.
He said the other boy and Ana started walking into the house, and he began to follow them.
But he said Boy A told him he would be fine, and told him he could go, and Boy B said he left.
He described again hearing a scream from the house. He said he went home, did his homework and continued watching his series.
But he said he could barely sleep and was worried about the other boy and Ana. When he was told Ana was missing, he said it hit his mind that his friend was with her.
He said the next day Boy A had bruises on his back and other injuries and he was wondering what happened to him and Ana. He said that was why he stopped talking to Boy A.
Once the news came out that she had been found dead, he said he realised that it was either Boy A or someone else who might have killed her. He said his thought was that Boy A ran away and "something else" happened to Ana. "Turns out that wasn't true," he said.
He told gardaí that when Boy A and Ana went into the house, that was the last time he saw them that day.
He then told gardaí that he had gone in with Boy A and Ana to the house, as far as the room, where Ana's body was later found. He said he left them just outside the room, because Boy A told him to leave.
He said he was just there to support Boy A.
Gardaí again urged Boy B to tell them everything, saying they knew he was holding back. The boy said he saw Boy A put his arm around Ana and "kind of like" hug her.
He said it was just a bit weird - he felt something was about to happen, so he left.
Urged again to tell gardaí everything, the boy said Boy A put his arm around Ana, and "kind of like flipped her" onto the ground, and he said, that was when he ran out of the house.
He then said he had seen Boy A start to choke Ana - he said he instantly knew what was happening - he was shook and did not know what to do.
Boy B said as Boy A was taking off Ana's clothes, he looked at the door where he was standing, and Boy B said he sprinted away.
He said Ana was starting to cry and kept saying "No, no don't do this". He said "it looked horrifying" when Boy A was taking off her clothes as he was choking her.
He said Boy A took off her t-shirt and threw it away. Boy B said he ran away just before Boy A started taking off the 14-year-old's bra.
The boy drew a picture of what he had seen at the request of investigating gardaí, showing Ana lying on the floor and Boy A on top of her choking her.
He said he did not see what was in Boy A's bag. And he said he could not tell the gardaí anything about Ana being sexually assaulted.
Boy B also acted out what he said he had seen with Detective Garda Daly.