Blood matching that of Anastasia Kriegel was found on a backpack, mask, gloves and knee pads seized from the home of one of the two boys accused of her murder, the Central Criminal Court has heard.
Holding the mask up for the jury John Hoade of Forensic Science Ireland said DNA on the inside of the mask matched both Ana's and the accused known as Boy A.
Another forensic scientist told the trial that DNA matching that of Boy A was found on Ana's neck and on tape that was wrapped around her neck when her body was found by gardaí.
The accused, who are both 14, cannot be named because they are minors.
They have each pleaded not guilty to murdering the 14-year-old Kildare schoolgirl at Glenwood House, Laraghcon, Clonee Road, Lucan on 14 May last year.
Boy A is further charged with the 14-year-old’s aggravated sexual assault in a manner that involved serious violence to her.
He has pleaded not guilty to that count.
Garda Hugh Andrew O'Carroll told Brendan Grehan SC for the prosecution that during a search of Boy A's home on May 24, 2018 he seized a backpack with various items inside from a wardrobe in Boy A's bedroom.
Mr Hoade told Mr Grehan he examined the bag and its contents on June 11, 2018.
Inside the bag were a mask, black woollen gloves, black plastic knee pads, black plastic shin guards, and a black woollen snood or neck warmer.
He found blood on the inside and outside of the bag and when he analysed it the DNA matched that of Ana's.
He described the mask as a "half mask" which had a hole for the eyes and nose and stops at the mouth where it is jagged to simulate teeth.
It has what appeared to be "simulated blood" around the mouth and could be secured to the head with an elastic band, he said.
He found blood on the outside and inside of the mask and again the DNA matched that of Ana's.
He tested the mouth area and found a mixed profile with all the elements of Boy A's DNA and that of Ana's.
He concluded that the mixed profile was most likely to be Ana and Boy A's DNA.
There was blood staining on both gloves and the knee pads which also matched Ana's profile.
No blood was found on the snood.
Mr Hoade also examined a bloodstained concrete block that was found at the scene close to Ana's body.
He said the blood on the block contained DNA matching Ana's.
Mr Hoade further examined runners, a tracksuit bottoms, a polo shirt and two backpacks which were connected to Boy B.
He found only one blood stain on those clothes and said it matched the sample given by Boy B.
Dr Brid Martina McBride of Forensic Science Ireland told Mr Grehan she examined footwear belonging to the two accused and compared it to a mark on the front of Ana's hoodie, which was found at the scene.
She said she couldn't rule out the possibility that the mark was made by the sole of Boy A's boot although she noted that other work boots have similar markings.
She said Boy B's footwear was excluded as the possible source of the mark.
Dr Charlotte Murphy said she is a member of the Sex Assault Team with Forensic Science Ireland.
She told Mr Grehan that she used a method known as "male specific DNA profiling" to analyze parts of Ana's body and clothing.
She found male DNA on Ana's neck and on blue tape that was wrapped around her neck and in both cases it matched Boy A's DNA.
She said the chances of finding that DNA in a person unrelated to Boy A would be one in 7,160.
She explained to Patrick Gageby SC for Boy A that due to the nature of the male specific DNA profiling method the statistical analysis is not like in other DNA profiling where the chances of finding the same profile in an unrelated person are often described as being one in a billion.
Mr Gageby suggested that if two people were "kissing or something like that" DNA could be transferred.
Dr Murphy said she does not determine how DNA is transferred but agreed that it is possible to transfer DNA when two people touch.
She said it depends on the nature of the contact and how long it goes on for.
The trial continues in front of Justice Paul McDermott and a jury of eight men and four women.