It’s been a long time-time gripe that, oddly, no estimated-time-of-death for Faith has ever been released (which might eliminate some theories), and I’m not sure how rough any such estimate would be, but this table I found gives some indication of what might be determined forensically:
********************
The table below summarizes the key changes which take place within 48 hours of death:
Time since death: …. Change observed
1-2 hours: ………Early signs of lividity. [blue-gray discoloring]
2-5 hours: ………Clear signs of lividity throughout body.
5-7 hours: ………Rigor mortis begins in face.
8-12 hours: …….Rigor mortis established throughout the body, extending to arms and legs
12 hours: ……….Body has cooled to about 25°C internally.
20-24 hours: …..Body has cooled to surrounding temperature.
24 hours: ……….Rigor mortis begins to disappear from the body in roughly the same order as it appeared.
36 hours: ……….Rigor mortis has completely disappeared.
48 hours: ……….Body discolouration shows that decomposition is beginning.
********************
The body was discovered around 11 am. We know KR left the apt. by around 4:30am., after the women returned home shortly before 3am. -- that leaves a small window of opportunity for those who believe KR killed Faith to have done so, basically between 3 and 4, or 7-8 hrs. before the body was discovered. Rigor mortis would’ve begun setting in.
I’ve always assumed that the murder occurred AFTER KR left but before sunrise (before 7am. and a lot of morning activity), which produces another narrow span of opportunity: ~4:45 - 6:45, or ~4-6 hrs. before the body was found, with less if any rigor mortis. [any later than that and there would be no rigor mortis, and I'm guessing we would've heard of that]
This may all still leave us in an ambiguous state… or, even if it works against the theory of KR committing the murder it yet allows for the possibility of her planning the crime and leaving the door unlocked for the perp (though again I think this was clearly a crime of sudden rage/impulse and not one of premeditation, jmo).