I haven't believed from the beginning that the BF was involved in her death. I think Miami LE is focusing on him because Miami already has such a bad reputation and they don't want to run away the tourist. LE would much rather it be an out-of-towner versus a local that did the deed.
Years ago my DH and I stayed there one night before leaving on our wedding cruise, we were almost afraid to go to sleep, DH had to keep checking on our car.
My guess at this time is that the boyfriend was not involved and the prime reason for that is what someone, oceaneyes i think, posted which is, it seems to me like it would be very difficult for someone to be seen with someone, kill them, and dispose of their body at three different locations miles apart when they are from out of town without a car, without leaving lots of evidence.
However, what we have is a couple that was fighting that morning when last seen together, and have had domestic violence charges in the past. Then you have the guy, I have no idea what he is like, but from the way he is being portrayed in the media he seems to be not a great guy, somewhat of a freeloader, sounds really like a suitcase pimp to me. When you put this together and you look at what usually happens when one part of a couple ends up dead like this LE would be crazy not to have this guy number one on the suspect list until they can rule him out. Like I said at least with the info we have at this time it looks like he was not involved BUT I think for the police to focus on him first was a natural and normal thing to do and did not have anything to do with politics or image management or w/e. In fact if they had not focused on him first I would think there was something strange about that.