I previously asked here about cryptocurrency and theft, and the answer was that bitcoin, unlike money, is not a negotiable instrument and therefore remains the property of the original owner when a thief sells it to a third party.

I asked about managing this issue on bitcoin stackexchange, and the answer said:

Regarding the question of ownership of stolen coins, that's really only applicable if your withdrawal is being funded from a UTXO that comes directly from a deposit of the stolen bitcoin. If the exchange previously combined that coin with other "clean" coins into one large UTXO (example transaction), then no one specifically can be pinpointed as having received the stolen bitcoin.

For an example of what this looks like, we can see this answer, that talks about the not stolen but famous pizza bitcoins:

There is no currently unredeemed output which contains 100% pure pizza coins. All the pizza coins have been diluted somewhat with other coins. The purest remaining are these 100 BTC which are 90.7276% pure pizza coin, and just 11 transactions separated from the pizza transaction.

And as an aside, he mentions stolen bitcoin:

Edit: I just found these 100% pure allinvain coins - undiluted after 24 hops from when 25k BTC was stolen from his computer.

Edit 2: I don't mean to imply that the allinvain coins haven't been thoroughly looted. They have touched 755,796 different addresses since being stolen and are currently sitting in 109,235 different addresses, including 8 from my own personal wallet. The exact same 8 as have pizza coins in them, it turns out.

Can we accurately legally say what is the situation regards claiming these "bitcoin"? If one had bitcoin stolen, and a transaction output containing X% your stolen coins arrived at an address of known ownership (say a large exchange such as coinbase), is there a value of X that would allow one to successfully claim the coins? 100%, 99%, 90%, 50%, 1%? Or any other property that would determine if such a case could succeed?