The Voice from the Grave

Charge: murder, first-degree. M.O.: shooting V with a handgun on June 1 and then escaping unseen. V is taken to the hospital and her condition deteriorates over the next five days. On June 6, in agony and gasping for breath, V says that her sister, D, shot her. V then dies. At D's trial the D.A. offers W, who heard V's declaration, to testify to its contents. D objects. What ruling and why?

What policy considerations generally support admitting such statements? In what respects are such statements similar to or different from admissions, declarations against interest, or excited utterances? Are they more or less reliable than declarations admitted under these other exceptions?