It surprised me that not one of them screamed or was able to scream as they were being attacked.
I’m wondering if went straight for the throat so they couldn’t scream.
Leathal plunges to lungs/heart + frenzy
There have been done who think one person couldn't have killed four people within the timeframe involved.
Considering how lethal a k-bar knife is, it's a wonder it
took as long as it did. About 11 minutes or so by my guesstimate.
(from what I recall, parking at ~4:06, noise at ~4:17, car speeding away at ~4:20)
If BK tool care to enter slowly, quietly, he might have reached the third level at ~4:10... I happen to think KG was awake, had investigated Murphy's reaction to activity (the Door Dash vehicle, XK opening the door, possibly BK's car, possibly the slider opening), told MM (95% asleep), "there's someone there" as she ran back up the steps (having seen either the DD car or BK on approach, but I lean towards the former), and in stealth, BK slinked in.
He had every nightmare advantage, plus a wicked weapon, he didn't need more than a mean minute or two to slaughter two victims.
He also knew he had "company" on "his six". (I watch NCIS. I practice copspeak.) He would have heard DM shout out. He knew he had matters to take care of, even as he was in his third floor killing field.
We will never know what XP heard.
Her house was quiet, EC possibly asleep. She ordered JITB, watched TikTok while waiting for delivery... did she eat it? On the first floor steps? Did she set it behind the kitchen sink? Did her earbuds prevent her from hearing the slider, Murphy, DM? Where was she when BK entered? She could have been sitting on the sofa and he didn't even see her and she didn't hear him.
When he came down the steps, was she in the kitchen? Did he walk her at knifepoint to her room? Why? Why would he even know which room to take her to? Or was she heading TO her room, from the kitchen, overtook her before she even knew he was there. Tells her not to worry, he's "there to help her".
By that point, EC would have been an unwelcome surprise and suddenly the bigger threat. He must have injured XP, moved to EC and killed him with force (the thud) before returning to a whimpering XK, then killing her too.
He was as efficient as he was evil.
JMO