Did they detect secondary (transfer DNA) on the sheath and not any other DNA ?

To find secondary transfer DNA on an object without detecting any other DNA, the scenario would involve a situation where a very small amount of DNA from a secondary source (like someone who briefly touched another person who then touched the object) is present on the item, while the primary person who directly handled the object shed minimal to no detectable DNA themselves, potentially due to factors like wearing gloves or having low shedding rates.