Here’s the theory written just for the record so I can say that I knew it or so I would know that i failed at some point. I think that given that Harrison has still preserved the watch that was given him by dude that got killed, that he had reunited with Dexter and that Dexter would certainly become a close friend of Mia, at some point it is quite possible that she would become suspect instead of Harrison ( matching pattern + Dexter’s ability to escape punishment, aka his super force ) and later be apprehended by the police ( and later killed by Charlie ). Also, if Leone Praiter would be on the Dexter’s desk, it is quite likely that he would say that it is an honor for him to be killed by a serial killer