People who actually are involved in LE and/or prosecution might have better information on this, but I do have a guess. Once they executed the warrant in Feb 2017, the police knew they had KAK dead in the water, defenseless. They could roll him up and put him away any time they wanted, right?
So I'm guessing they MIGHT have agreed to postpone arrest(s) while they were investigating something else--like L&A's murders. My guess would suggest that LE put the finger on KAK to help them with the Delphi investigation (which suggests that KAK *does* have some involvement, even if it is only clues to the murderer(s.) KAK agreed (in my supposition) to assist the police, to postpone his arrest and perhaps even buy a bit of favorable treatment. Though based on the probable cause affidavit, he's not going to get MUCH favorable treatment from anybody, nor does he deserve any.
And if they did agree to postpone arrest, I feel sure that they would only have done it if they were certain they could monitor him and make certain no other underage girls were endangered. IMO only, but I can't imagine LE taking *any* chance on that. Especially if KAK really does know or suspect who the murderer(s) is.
Side issue: A few messages above, there's discussion about KAK being arrested "at his girlfriend's apartment." I haven't seen anything about her so far. But I find myself wondering what kind of girl says, "Sure, you can come live at my place until the police get ready to arrest you for child











! No problem!" Heavens above.