We know the cause, therefore we can look at the effect and determine the cause.
The problem with applying this 'forensic method' is that you do NOT know the cause. That's kinda the point isn't it?
Not to mention it's logically fallacious. A -> B does not mean B -> A. Logical implication is not bi-directional.
A forensic scientist would never be so foolish as to say, ?I?ve never seen a wound like this before. Therefore, it must have come from a Martian Death Ray, which proves there must be life on Mars.? The conclusions of forensic scientists are always based on observations of effects with known causes.
Evolutionists routinely find fragmentary fossils (a piece of skull, or a single tooth) unlike any fossils that have ever been seen before. Based on this single type-specimen, they define a new species, and confidently say what creature it descended from, and what creature it evolved into. That?s not forensic science. It?s not science at all. It is speculation based on the assumption of evolution.
The fallacy in their argument is that they believe they can reason from an effect they have never seen before back to a presumed cause that has never been observed.
The counter argument to this actually exists. There have been dinosaur species, thought to exist, where strange remains were found with them. Further strange findings caused a later conclusion that the original species did not exist, but, in fact, were because of two different species being found at the same location, with the strange fossil findings being the parts missing of those two species.
Science doesn't, as you insist, go 'Hey look, this is odd, it must be a martian death ray!' What it DOES do is go 'Hey, this is odd. We should examine this further.' Then it makes hypotheses.
The only time science says something for certain, is when it has been tested with rigor, when evidence has piled up. So, it's not going to say 'It's a martian death ray' until they've discovered enough of them, on mars, at the scene of a war, with dead martians from wounds that look like they were caused by the death ray.