Good points on some of the hypotheticals,
@SLouTh.
Regarding the ""alibi" at the incorrect time" hypothetical:
I've often wondered what would happen if the timing(s) of the murders were determined to "be off by an hour" that night, for example, and what that would mean in the context of the murderer's whereabouts, where they may have been captured on cameras, their alibi, etc.
An "aha ! moment", if you will, on how crucial the proof of timing of different things could be, and whether LE has evidence and BK has an alibi, that would come together and shake hands, all at the right times within that window that night.
IMO, that window begins when Kaylee's & Maddie's cellphones are used to make the calls to Jack that go unanswered because he was asleep -- last 'proof of life' if you will, although it's not been proven that it was them using their phones to make those calls, AFAIK.
IMO, that window ends when the white car seen on video camera(s) driving near and turning around by 1122 King Rd is seen driving away from 1122 King Rd.
I say this regardless of routes that could have been taken by a white car that was seen driving up to ETA: their house) and in and out of the victims' neighborhood. I don't personally have anything to add to speculation on that discussion.
Although I find it somewhat of interest to look for proof of routes taken and what kind of white car went which way that night and what they might have been doing and how quickly or slowly, personally I'm mentally "backing out" to reframe the big picture timeframe window, during which anything could have happened.
I'm sure LE and the prosecution have lots of evidence to help narrow things down "to the hour", but not "to the minute", IMO, so a minute here or there doesn't matter that much to me.
All MOO.