Of the almost 1,500, we suspect there's a 'nugget' who are...

Of the almost 1,500, we suspect there's a 'nugget' who are truly missing ? washed out into the Gulf. Then there's a small subset that honestly don't want to be found. How do we know when we're done? How long do you keep looking? What do you do when you've done all the DNA testing you can, when you've called everyone and you still can't find the person?