The potential presence of the DNA profile of the man accused of the murder of Nikki Allan on her clothing has been the subject of evidence in his trial today (Tuesday May 7).

A jury at Newcastle Crown Court, where defendant David Boyd is on trial, was told DNA technology has advanced considerably in the three decades since the original investigation into the killing of the seven-year-old schoolgirl, in Sunderland.

Forensic scientist James Chapman told the hearing that in his 22 years in the role, giving such evidence in cases, the advances have improved the ability to be more reliable giving DNA comparisons.

He said the use of Y DNA profiling has enabled scientists to only search for male lineage DNA.

Read more: Nikki Allan: Jury in David Boyd murder trial told how body was found

The court heard part of a re-investigation of the unsolved case in recent years included the forensic re-examination of the clothing worn by Nikki on the night she was killed.

Her stabbed and battered body was discovered dumped in the basement of the derelict Old Exchange building, off High Street East, Sunderland, the following morning, October 8, 1992.

Mr Chapman said DNA lifts from her t-shirt and leggings included two profiles which have a 28,000 to one match with the DNA of the defendant or his male family members, none of whom lived in the Sunderland area at the time.

There were also two mixed profiles carrying a 5,100 to one match, elsewhere on the clothing.

He said the areas of the clothing from where the matches were recovered were consistent with the theory that that was where there would have been contact if a girl of the stature of Nikki at the time was lifted into a gap in a boarded-up window at the rear of the disused building, said to be the only point of entry.

The profiles were found on the neck collar, under the arm-pit and at the bottom of her t-shirt as well as on the hip of her leggings.

Since his arrest, in 2018, the defendant has offered the possible explanation for the presence of his DNA on her clothing as the fact that he would sometimes spit over the balcony of the Wear Garth flat complex where both he and Nikki’s family lived at the time.

He said Nikki and other children would play below and some of the defendant’s saliva may have contaminated her clothing.

Read more: Nikki Allan: Jurors see photos and sketches of suspect David Boyd

Asked about the possible theory that was the source of the DNA profile on her clothing, Mr Chapman said the presence of saliva was not detected on tests on the garments.

Under cross-examination, by defence counsel Jason Pitter KC, Mr Chapman conceded it would potentially be possible for a DNA profile not from Boyd’s family lineage to be shared by someone else.

But he said the statistical probability of an unrelated male having the same match would be one in 28,000.

Asked about cross-contact, Mr Chapman said there was a possibility of the DNA profile getting on the clothing other than by direct contact.

Under re-examination, by prosecuting counsel Richard Wright KC, Mr Chapman said, in reality, he was unable to be certain how the DNA got onto Nikki’s clothing.

Read next:

* LIVE: Man stands trial for murder of Sunderland schoolgirl Nikki Allan

* Nikki Allan LIVE: Murder trial continues in death of seven-year-old

* Dad of Nikki Allan searched all night for murdered girl

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Asked about the other 839 DNA profile samples taken as part of the investigation, mostly from men in the Sunderland area, Mr Chapman said only those of the defendant and a sibling, not from the North East, matched.

Boyd, 55, of Chesterton Court, Norton, Stockton, denies the charge of murder.

His trial continues tomorrow (Wednesday May 3).