It is a sample from the strap (upper and lower) and underside of the button.
RN after reading the report during testimony
A. The entire leather portion of the strap, both top and bottom, and then the underside of the button.
Item Q1.1, the sheath strap and inner snap
Beyond the expertise of a crime analyst.
2019 van Oorschot et al
The article is an illustration of how extremely complex the question of how and when is given the identification of a sample that has no biological source such as blood.7
Despite this wealth of information and scientific study, the authors conclude that more work is necessary and that the expertise to offer activity level opinions, the how and when, is beyond the expertise of crime lab analysts.
2024, NIST
the EWG
But a further important question is what activities led to the presence of that DNA. With the increased sensitivity of DNA techniques and sophisticated software, a DNA profile may be developed even when the contributor of that DNA never touched the item or area that was swabbed. Alternatively, a person’s DNA may be present when they were not involved in the crime.
“Except in ground-truth-known experiments, where an individual is observed to have been in contact with a surface/location, it is not possible to know whether the transfer was direct or indirect.” (Id. at §7.2).
JMO