I think that 《嗜血法医》 may have been "poisoned 或者 drugged" himself and that is why he see's Doakes 或者 it might be just like him seeing Harry. All things considered I think he might be arrested in reality and then comes clean saying that he (Dexter) faked Doakes death and really Doakes was killing for 《嗜血法医》 thats is why the killing's were still going on. I know it's a ridiculous idea. :-P
Well, he's not going to jail (permanently), that much is certain. There's still another season so that can't happen till the end of the series (though I doubt they will end it this way). He'll get out of this somehow and live to kill another day.
