A Garda who spoke to two boys accused of Ana Kriegel's murder says he was unhappy with accounts of their movements through a park near her home on the day she went missing.
The boys, who are aged 14, both deny murdering the schoolgirl - and one of them is also facing an additional charge of aggravated sexual assault.
It is the prosecution's case that Boy A violently sexually assaulted and murdered Ana Kriegel on May 14th last year.
The allegation against Boy B is that he lured her from her home in Leixlip and helped his friend cover-up what happened.
Both boys have pleaded not guilty.
Today, Sergeant Aonghus Hussey gave evidence of walking through a park near Ana's home with the two boys the day after she went missing.
He said he wanted to go over the route they said they had taken with her the previous day.
Boy B said he had brought her there to meet Boy A so they could discuss "relationship issues".
Sergeant Hussey said Boy B seemed "uncertain and confused" when he pointed out they were walking a different route to the one he indicated.
He said he felt something was wrong when Boy A gave Boy B a look at one point, and he claimed their accounts lacked consistency.
Ana's naked body was found in a derelict building in Lucan a few days later.
Reporting by Frank Greaney