Answer:
See my explanation!
Step-by-step explanation:
I'm unsure whether the noun you are referring to is "police" or "dog" because I don't see any underlined word- I'll just answer for both and hope it helps.
"Police" is referring to who is doing the finding, which is the next verb. We can infer several things based on this noun. "Police" implies that there is a reason to consider the dog's death a crime, or, at the very least, something to be taken seriously. The purpose of the word "police" is essentially to show the importance of the death.
"Dog" is referring to who was found dead (by the police, as mentioned). This noun simply exists to shed light on what died- without this noun, there is no subject associated with the word "dead", which makes no sense. The purpose of the noun "dog" is to specify that a dog is what died.