Just playing "Devil's Advocate" for a moment...
LE obviously knows more than we all do, but while I see plenty of Probable Cause for an arrest, IMOO I still don't see anything so far in the public domain that proves he was the one that committed this murder beyond a reasonable doubt. Yet it seems that he's already "Guilty As Charged" in the court of public opinion all over the internet, rather than innocent until proven guilty. (My guess is they'll have a request a change of venue for his trial.)
Imagine this as a Law & Order SVU episode...
Nate passes out in a room at the apartment he's staying at where there's a party going on, and someone sees him passed out on the bed, comes in and roots through his pockets for drugs. They find his keys and steal his car. They pull "fake Uber" and pick up a girl, intending on assaulting her but things go wrong and they end up killing her.
Now they have to do something with the body and the blood-stained stolen car, and implicate someone other than themselves. Firstly, this guy is much bigger (say 6'2", 220 lbs) than Nate's 5'8", 155 lb frame and is easily able to put this 5'7" girl into the trunk. He either already knew where Nate used to live in New Zion because they happened to go to high school together, or can he see the New Zion address on the registration.
He drives her to within 1.5 miles of that address and carries her 50-60 feet off the road in the dark and leaves her above ground, in a spot where she's found less than a day later by turkey hunters (who also coincidentally went to high school with Nate). After leaving her body there, he drives back to Columbia and drops the car back off where he stole it from, wipes the steering wheel clean, wipes Sami's cell phone clean and leaves it in the glove box, and takes off without going back in the apartment.
The next morning, Nate wakes up and can't find his keys which are usually in his pocket. He finds them outside in the car, parked where he left it, with the keys in it and assumed he must have left them there. Due to the glare of the sky on the driver's side rear window, he doesn't immediately notice the blood in the back seat (I don't look in the back seat when I get in my car either.)
He goes back inside to sleep off his rocking hangover and watch Netflix for the remainder of the day, putting a few posts out on Facebook here and there in the evening. At some point late that night he discovers the blood. Maybe he realizes he blacked out for a bit before passing out the night before and so he's not sure what the hell happened, and whether he was involved or not, so he doesn't immediately call the police while he's trying to figure that out. Freaked out by all this, he calls his close female friend and picks her up. He hasn't seen the news that day, and she tells him that he better clean it up the car because it's all over the news that a girl was murdered in a car just like his so whether he did it or not he will burn for it. They go buy bleach, wipes, etc., and on the way back get pulled over by LE. He panics and runs.
***********
The fact is we don't actually know who was driving that car when Sami got in it.
It also seems bizarre that he'd come back to Columbia and ride around in the same area with a bloody car if he knew he did it and that it was her blood and her cell phone in the car too.
I would have fled, and perhaps taken the body with me to another state before dumping it -- not go out of my way to leave her body right out in the open (not hidden in the pond) 1.5 miles from my former house, KNOWING that my car (and possibly my plate) would probably be on video (there are city-owned surveillance cameras all over Five Points that are marked as such with signs, from what I read).
Just wanted to present another possible narrative...feel free to pick it apart...LOL!!
ETA for clarity