Fabian Castillo is most certainly in Turkey, but it is not certain he'll be staying.
What follows is an admitted mix of conjecture, speculation and gluing together pieces of info gathered from various sources, but what is clear is this: As of Friday, Major League Soccer and the Turkish club Trabzonspor had yet to come to an agreement for Castillo's sale. This also provides some reasoning behind the bizarre level of silence from FC Dallas over the last week.
Here is what we do know for sure. Sometime in late June FC Dallas was made an offer to buy Castillo from Trabzonspor and Dan Hunt framed it that Castillo chose to decline the offer himself.