Personally, I would have no problem finding an excuse to convict would-be Reagan assassin John Hinckly in James Brady's death. But I have to agree that it would be virtually impossible to establish that the direct cause of Brady's death was an act committed 33 years ago. Certainly Brady's persistent health issues were caused directly by his being shot by Hinckly. But can you say those health issues were the direct cause of his death?
Playing devil's advocate I suppose this is different from someone who recovers fully from a gunshot wound and then dies 33 years later. But is Brady living with the effects of the attack for the rest of his life the same as dying from it?