To safeguard against contamination or accidental DNA transfer, particularly in forensic laboratories, Boise State University researchers developed a 120-basepair tag to be used as a way to identify samples. As they report in the Journal of Forensic and Legal Medicine, these nullomer barcodes, made up of DNA sequences that are not found in people, could be added to collection devices so DNA samples are tagged upon collection. Further, the researchers note that the barcode could reflect where and when the sample was obtained.
"If a suspect's DNA was tagged and then accidentally mixed with a crime-scene sample it would place them at the scene when perhaps they were not. But the tag's presence would prove that particular DNA sample came from sloppy lab or forensic practice and not the suspect," the New Scientist notes.
The Boise State researchers also show that if they diluted a tagged sample a million fold and drizzled it onto a knife, they could still detect the nullomer tags.