Has it been mentioned if Holly locked her home?
The main thing I would like to know if there was any sign of forcible entry. But if she was just running her son to the bus stop like she did every morning she might not have been in the habit of locking the front door since she would be returning soon and an intruder could have entered freely without leaving damage.
Holly's mother said that after Holly returned home from taking her son to the bus stop Holly "normally had a cigarette and coffee as she watched the news before going to work and it appears she was doing that when someone interrupted her" That tells me that Holly apparently had enough time after returning home from dropping off her son to at least pour a cup of coffee and possibly have a cigarette, since the coffee cup was apparently found on the floor. No mention if there was a burnt cigarette found, but I'm just going off what Holly's mother said. From this I would have to conclude that neither Holly or an intruder were startled when Holly returned home. Most (mobile) homes are set up where you enter though the front door, you enter either the family room or kitchen. Obviously if Holly poured herself a cup of coffee the intruder (if there was one) wasn't in the front part of the home. I would also think that if there was an intruder in the home when Holly returned the intruder would have likely made an exit out the back door and not confronted Holly. The statistics for the home owner to be confronted by intruders during burglaries is low.
If Holly would have ventured to the rear of the home where the bedrooms are likely situated and encountered an intruder there I doubt there would have been signs of a struggle in the kitchen area if Holly was removed out the rear door as it appears that might be the case since it was reported by a neighbor that the rear door was ajar. Unless Holly ran to the front of the house and was caught by the intruder.
Now I guess the cup of coffee could have been poured prior to Holly leaving the house to drop off her son. Which would leave open the possibility that Holly did encounter someone as soon as she entered the house, a struggle ensued and the coffee cup that was there prior to Holly leaving was knocked off the table when bumped and her glasses also ended up being knocked off.
I wonder if Holly's son was questioned and what his answer was if asked whether or not his mother normally locked the house when they left for the bus stop or if his mother normally has a cup of coffee prior to leaving or if she had a cup of coffee prior to leaving on the morning Holly when missing.
But if there was a burnt cigarette butt found on the floor as well, that would tell me Holly spent some time in the home after returning from dropping off her son and prior to any altercation with an intruder or an acquaintance. Who lights up a cig when they return to find an intruder in their home as soon as they walk through the door?
If Holly normally locked the house and no forced entry was found, that points to someone Holly knew.
JMO