Blood spatters on the boot of one of the teenagers accused of murdering Ana Kriégel showed the boy either assaulted the schoolgirl or was very close to her when she was assaulted, the Central Criminal Court has been told.
Two 14-year-old boys deny murdering the 14-year-old girl in a derelict house in Lucan a year ago. The first accused boy also denies violently sexually assaulting her.
An expert in DNA and blood spatter analysis examined the black boots worn by the first accused boy, on 14 May 2018 - the day Ana went missing.
The court has heard Boy A told gardaí she stormed off after he told her he was not interested in her in St Catherine's park in Lucan, and that he was later attacked by two men.
John Hoade said he examined the boy's boots for blood staining. He said the soles and upper areas of both boots were blood stained. He sampled nine separate areas on both boots and the DNA profile in all areas matched that of Ana.
Mr Hoade told the court the blood staining was not immediately obvious and he used a microscope to magnify the areas.
Some of the blood could be identified as blood spatter - particularly on an area of the right boot. He explained that this kind of pattern comes from blood flying though the air after an external force has been applied to it.
He told the court the pattern indicated Boy A either assaulted Ana or was in very close proximity to her when she was assaulted.
Mr Hoade also examined a piece of wood found in the room where her body was found. The stick was shown to the jurors who were told it measured 92cm in length and 4x3 cm in width.
It was charred at one end and a nail or staple protruded from each end.
Mr Hoade said he noted that the stick was blood stained throughout and the DNA profile from samples taken of the blood, matched that of Ana.
He said the blood patterns on the stick were those he would have expected to observe if the piece of wood had been swung through the air and used as a weapon in the assault of the schoolgirl.
He also examined a concrete block which had blood on all six surfaces.
The block was found in the same room in the corner where Mr Hoade had noted heavy blood staining.
He told the court it was around half of a nine-inch concrete block, which was quite heavy and awkward to manipulate. He said there was also hair attached to the block.
He said he did not sample the blood from the block as it was his understanding there was no suggestion it was used as a weapon in the assault.