The autopsy permission form was taken from Baptist Memorial Hospital to Graceland shortly after Elvis was pronounced dead on August 16, 1977.  The form was to be presented to Vernon Presley for his signature, and information about the autopsy procedure would at that time be provided and explained to him.  But right before this discussion took place, Vernon had to have been notified that Elvis was dead.  Who told him?  And who then talked to him about the autopsy?  My analysis is linked here.

UPDATE :  Further comments on the autopsy permission form from Dr. Nichopoulos, illustrating that it was apparently he who initiated and handled the situation, not Dick Grob:

Nichopoulos:  “…it was left to me to break the news to Vernon that his boy was dead.”

When Nichopoulos told Vernon that Elvis had died:  “Vernon heard me without understanding the meaning of my pronouncement.”

Dr. Nichopoulos notes that Vernon initially refused to grant permission for the autopsy, but that he was persuaded by Dr. Nichopoulos’s plea that he needed to “know if I did something wrong.”

Dr. Nichopoulos says he walked away from Vernon after Vernon refused to grant permission for the autopsy, but that Vernon then called after him, instructing Nichopoulos to make sure they “put my boy back together.” 

Nichopoulos does not mention the autopsy permission form.

Nichopoulos:  “I took an authorization from the emergency room and went out to Elvis’s house to tell his daddy what had happened…”

Nichopoulos:  “I don’t recall [seeing Dick Grob at the hospital].  I don’t remember whether he was in town or not.”

Nichopoulos states that he decided an autopsy should be performed, that he got the autopsy permission form from a nurse, and that he would tell Vernon and Minnie Mae [Elvis’s grandmother] about Elvis’s death.

Nichopoulos says that, “…I related the news to them [Vernon, Minnie Mae, and others in the room], and I talked about things for awhile.  And then somewhere in the course of events, I asked him for permission for an autopsy, which he granted.”

At no time does Nichopoulos mention anything about Dick Grob dealing with the autopsy permission form, nor speaking with Vernon at Graceland.  And while these statements from Nichopoulos are not totally consistent from account to account, they nonetheless are consistent on the overall narrative.