In the two-minute clip, you see the toll -- SPOILER ALERT! -- LaGuerta's murder has taken on Deb.
Of the decision to bring his serial killer series to an end, Michael C. Hall tells EW, "I've been an advocate for having a dialog with the writers and getting a sense of how to best bring this story home -- not wrap everything up with a tidy bow, but find some sort of conclusion. There has to be an end game. Once Deb found out, it felt like we were moving toward a place where the world as Dexter knew it would end."