dead birds?
I provided you with several links actually regarding duration of DNA.
Here's another fYI, bearing in mind we do not know source of the three DNA samples.
Indoor scenarios
For an exposure period of up to 9 months, nearly all blood and saliva samples stored in the dark resulted in complete profiles as expected (Fig.
1), since especially blood samples collected on paper or cloth are routinely stored for much longer time frames. Rather surprisingly, only 50% of blood samples and 75% of saliva samples demonstrated all alleles of the responsible individual after an exposure of 12 months. This can possibly be explained by the use of plastic as supporting material as well as the rather low amount of 20 µl blood in some samples, since these samples showed the most allele losses. Moreover, we often observed a flaking of blood samples thus reducing the amount further. Regarding epithelial abrasions, the results are quite different (Fig.
1). After 3 months, only half of samples demonstrated a complete profile, after 12 months none, not even those in the dark. Here, not UV radiation as expected but another factor seems to be relevant. Possibly the different composition of the bacterial fauna on the skin compared to, for example, the bacterial fauna in saliva could have an influence [
34].
DNA persistence and DNA transfer are important features in the assessment of a crime scene. The question how long DNA may persist at a certain location is similarly important as the one how the DNA has been transferred to this location. Depending on the source of the DNA as well as the...
link.springer.com