Hello, Newbie here. I've been lurking for some time, finally joined WS and wanted to comment on this case.
BTW, MissD, OldSteve, Bernina, Luvrosco, nancydrew71, enzeder, Lilac7 and the rest, you are all very good at this. Also, thank you OldSteve for adding #6 and #7 back into the mix.
I would like to start by saying my deepest sympathy goes out to all those who knew Allison. By all accounts, she was a special person to many people and did not deserve to have her life cut short in this manner.
I know speculating can be offensive to some people, but all we can do to help is offer our opinions. Who knows, maybe something will be said that triggers someone to remember something that leads to putting the person or persons responsible for this atrocity behind bars and give Allison's family and friends a modicum of closure.
So...here is my 25 cents worth (Encyclopedia Brown reference - when I get to it, this will become part of my signature):
LE has DNA.
LE says person may have scratches on hands and arms and may try to give someone the bracelet. IMO, they have probably already ruled out the BF...as the perp. I'm pretty sure LE has checked his hands and arms for scratches and they are most likely already testing (or have tested) his DNA.
Then again, we also know that a large portion of these cases are committed by someone very close.
So...IMO either a professional was hired to commit the act or maybe a professional was hired to clean up after an accident.
IMO the BF knew potential danger loomed from someone trying to hurt or punish her or him, thus the security system.
Did someone hire a hit to stop the pending marriage?
Did someone with financial ties to Allison hire a hit?
JMO...but a hit would possibly make sense considering we don't know if there was a sexual assault and the missing items don't seem to make a lot of sense for burglary. We do know however that the perp likely tried to clean up everything with bleach or some sort of cleaner. IMO...the missing items are probably an attempt to stage a robbery or even more likely try to clean his DNA from those items that he had probably touched in a scuffle. A professional might have even bugged the place and listened to AF tell her BF to go home and study (thus, he knew he had time). A professional would also take his time to clean up the scene to the best of his ability (especially if he felt he had time).
The hired hit theory would explain why LE thinks it is "targeted" and not a worry to the community and for the community not to worry about a serial rapist, etc. The "personal" part may just be a LE theory. A head covered in cloth could mean blood containment, or maybe someone tried to stop the bleeding or maybe the perp knew her enough to not want to see her while he disposed of evidence.
IMO this is just one possible theory that hasn't been explored much yet and should at least be considered further.
I look forward to sleuthing with you all.
P.S. I promise to keep my posts more brief in the future.