Not sure what OCME stands for but I find it really, really strange they won't give answers to main detective of her case.
It is very likely they do not know or have no records but it seems they all are worried of consequences of some mess from 30 years ago rather then simply saying to detective they do not know. But again, why so worried about that now? I wonder if there is different reason they all not cooperating together or unable to release information between each other. Some restriction on her case? Or some other strange reason?
We all assume she was burried, we have no confirmation of that yet... And if she was it could have been month or even quite some time after her demise.
Now, we know that original detective of her case passed away and case went through many detectives. But what about original coroner/medical examiner? Is it possible to trace who it was and arrange some kind of small interview?
I would suggest also to call or email local coroner/ME about what were their usual practices at that time. How long usually they kept the body and where they usually send them for burial. If it was send to different places or certain specific area. If length of keeping the body was different in case of unknown deceased. I would probably not ask them specifically about MVJD case, but just these information in general. This might not give us all answers but it might send us at some direction of search.