I have always said the bloody canopy should have been removed and saved as evidence. Would it break the case, nope but it would have made "RCI" look more like they were doing everything they could to help. But there I go being logical again.
Realistically, you can't expect people who work in other fields to think of these issues because they are not trained in law enforcement. The staff on the ship probably would have done so if either the initial (Turkish) investigators or the American F. B. I. agent who witnessed their work had simply asked.
That said, I think that the photographs of the bloodstains on both the canopy and the hull should be sufficient for evidentiary purposes.