Until I see otherwise, I belive it is HIGHLY LIKELY that Nick Holbert is the perp.
I subscribe to Occam's razor, which summarized states thusly:
"Other things being equal, a simpler explanation is better than a more complex one."
Every explanation involving Holbert being the perp is relatively simple to determine. Every explanation involving anyone BUT Holbert is, at best, difficult to determine.
Here are the tells:
1. FACT: Last person to admit seeing KB alive.
2. FACT: Holbert is an RSO with a crime against a child (albeit when he was a teen himself, but a teen with adult knowledge if not experience)
3. FACT: RSO's who have committed crimes against children are far more likely to escalate to murder than a civilian never having commited a crime of sex or violence. John Gardner and John Couey come to mind.
4. FACT: He was arrested for FTR with a bond of $100,000, which is the highest amount I've ever heard for a straight FTR charge. As I stated earlier, most FTR's are in the $10,000 range, perhaps 25,000 if he was actively hiding and had to be tracked down. Someone of Nick's RSO past, with no FTR arrests, would normally be assessed a low level or even OR; a $100,000 means they don't want him to go ANYWHERE. Why? Occam's Razor...
These four facts are unique only to Holbert and no other POI.
Now, the only three known principals have only innuendo working against them.
Husband Mike B.
1. Both alibied and unlikely to have driven from Florida back to NC, then back to Florida, too many ways LE have to determine such travel, and too many people to lie in his behalf.
2. Marital troubles: At best, a separation; while providing motive, considering the thousands of separations that occur every day, coupled with Mike's disposition, even less likely.
3. Not "perfect" in TV appearances: On the surface, ridiculous. Considering his wife may be missing, there is no way to predict behavior. (In addition, note I didn't invoke any behavioral attributes to Nick in my assessment.)
4. Former trouble with the law: Probably the most "damning," but in general, if the crime is not related to violence or sex, would have greater chance of rehabilitation than those who were violent or an RSO.
Friend Justin
Not enough information, but from what little information I saw means he's extremely peripheral.
Bar Owner Steven Cantrell:
1. Completely out of character for someone who runs away from problems to suddenly go the other way with a stranger or not someone related to his problems. He had everything to gain maintaining a low profile. He was probaly the most pissed person not associated with the victim, as his life is pretty much over financially.
2. Unless it turns out he had a secret relationship with Kelli (highly, highly unlikely), he wouldn't have had any motive that would override his need for overexposure to his own background; hence his legal problems.
3. It is worthy to note that he essentially got a walkout bond with regard to his multi-hundreds of thousands of dollars he owes in child support and running away from a court appearance, which means that LE is convinced he is not involved with Kelli's disappearance, otherwise they would max out HIS bond. Indeed, they could bond him up to the amount he owes for child support plus whatever bond he would be required for running away from a court appearance; easily over $100,000. But keeping someone in jail costs about 60 bucks a day or so, so the prosecutor doesn't believe the risk warrants a high bond.
OTHERS:
Too many variables come to mind. Using Occam's Razor, I would probably look to someone not named, such as an unknown bar patron who may have secretly followed them (complete stranger) or know of Kelli in ways we don't know, BEFORE Cantrell or Justin. So far, I haven't seen any indication of that.
Therefore, my conclusion: Only one POI in my book, Nick Holbert.
Obviously, I myself am biased, but unfortunately that bias is based upon rock-solid experience.