The judge in the trial of two teenage boys for the murder of 14-year-old, Ana Kriégel has told the jurors to exclude normal human sympathy and empathy from their deliberations.

Mr Justice Paul McDermott has begun his summing up of the case to the jury.

Both 14-year-old boys deny murdering the schoolgirl at an abandoned house in Lucan in May last year. 

The first accused boy also denies aggravated sexual assault.

Mr Justice McDermott told the jurors they should bring their life experience to bear on the facts of this case, including their experience of childhood and of telling lies. 

He said a murder trial would normally attract high emotion and feelings and very, very strong emotions ran in this case "for obvious reasons".

He said it was essential for the jurors to be independent in mind and act on the evidence. 

He said it would be impossible not to have sympathy and empathy for the bereaved family in this case. 

And it would also be impossible not to have a degree of empathy for the families of the accused boys and the situation they had been placed in. 

But he said they must clinically analyse the facts of the case and exclude the normal sympathy and empathy they would have.

He suggested they might find it useful to consider the evidence against Boy A first before proceeding to consider the evidence against Boy B. 

He said that was the way the prosecution had presented the case. 

He also reminded them that the accused were very young as were some of the witnesses and this should have some bearing on the way the jurors approached the evidence.

Mr Justice McDermott said there had been limited cross examination in the trial.

What would be a matter of great importance to the jurors would be the interpretation of the sequence of events put before them.

The boys were entitled not to give evidence in their own defence he said, and that could not be held against them.

The judge said they should examine carefully what both boys said in garda interviews along with all the other evidence in the case.

But he warned them that they could not rely on something said by one co-accused when considering the case against the other boy.

Mr Justice McDermott said the jurors should carefully consider whether they could draw inferences from certain facts. 

He suggested they might consider, for example, evidence about a copy book containing information about a "satanic club" to be a distraction or irrelevant to the real issues in the case. 

He told them not to put strained interpretations on what they would normally regard as "teenage messing".

The judge said he had "considerably more" to say to the jurors and the issues in this case were very serious.

He'll resume his charge to them in the morning.