Examples 1 and 2
Visual inspection of Examples 1 and 2 revealed they were both of similar age, type and condition. Neither had a stamp. The seal was tested on both and Example 1 returned a relatively high amount of DNA, while Example 2 was just under the cut-off point for further progression.
These results are indicative of the fact that it is not possible to determine simply by visually inspecting the envelope whether sufficient DNA will be found.
Examples 3 and 4
Visual inspection of Example 3 revealed a 3/4s intact seal and a stamp on the front of the envelope. Extraction of DNA was undertaken on the seal of Example 3 and no DNA was found. The seal on Example 4 had separated over time and was therefore not suitable for testing.
The stamps of both Example 3 and Example 4 were tested and Example 3 had a higher yield of DNA than Example 4, even though Example 3 was over twenty years older. Both had sufficient DNA to progress to the next stage.
As with Examples 1 and 2, these results are indicative of the fact that it is not possible to determine simply by visually inspecting the envelope whether sufficient DNA will be found.