Ok, I don't guess I can explain my theory but I'll give it one more try.
It could only possibly be evidence if it is likely to be Caylee's. There is no way to determine if it is likely to be Caylee's unless LE can find similar horses, or pictures of the same horses in the home. So that's the first part - see if it is likely to be Caylee's by finding other similar ones or photos. If no matching horses or photos are found, then nothing further would be done with it, IMO. It will sit alone in an evidence box forever.
If it is determined through matching to other ponies in the set, or through photos to likely be Caylee's, then it could be important in one of three ways:
1. Part of a long list of items from the home that ended up with Caylee. So the jurors might hear something like, "100% of the items found at the crime scene match things previously photographed at the A home. The following things from the home were found at the crime scene... this horse pictured here from Christmas 2007... this book from July 2008... this laundry bag seen in this shot of KC's room, May 2006... this WTP blanket pictured here from August 2006". Then the defense could
try to bring witnesses to say that there is no proof that this pony is the same pony pictured, but who could say for sure? In fact, a photo of the pony might show some identifying marks that might make it even harder to doubt - like did the dogs chew on his leg? Did he get colored on with a marker? If he had real "hair" did he have a haircut at some point? I think if police found a decent photo match it would be hard to refute.
2. Evidence could be on the pony. Potentially it could have been used as a weapon, I suppose. There could be blood spatters or smears on it. There could be something written on it, attached to it, taped to it with duct tape. From this search warrant we have no idea if there is anything special about this horse at all, just that they want to know if it matches some at the house or if there are photos of it at the house. There could be lots more that we do not know about the state of the horse.
3. Finally, like I said above, it could be kept for the future time when some ZFG confesses and we can use our super advanced "breath DNA" (I made that up!) to see if she ever breathed on this horse. Ten years from now they would be happy to know if anyone ever determined the horse was
probably Caylee's.
But I get what you are saying, so what? If it is proven to be Caylee's and the prosecution says the above statements from #1 to the jury, well then the defense can just say, yeah well the nanny had a key so she must've taken the toys too. And they could say that via CA's testimony- but the jury is only going to buy that if they buy that there
was a ZFG. So far we have about zero evidence that ZFG exists so I think the jury can put together that if most or all the items at the crime scene came from the house, where they had to be obtained by someone with a key, and only the four family members and an imaginary nanny had a key...
I guess maybe the opposite approach might be helpful. What if they did
not try to find out if the horse was Caylee's? Could the defense then bring that up and say, "This horse found at the crime scene, has it been verified to be from the A home? No? You didn't even check? Well, then perhaps a stranger killed her! Perhaps you are trying to frame KC! CA, GA, have you seen this horse before? No? Ah-ha! Reasonable doubt! This horse was found inches from her body and no one even bothered to identify it! Kick the prosecution off the case, they are biased and unfair!"