Your past few posts had me convinced (so good job making a case!) but now I'm not sure. If they knew he was in WA and they knew who he was and they had probable cause for the arrest, why wouldn't they arrest him in WA/ID and not have to deal with the long trip to PA and extradition? What if he intentionally crashed his car on the drive home killing himself? Seems like a risk to not pick up the person as soon as you believe you have probable cause for an arrest.
I am leaning towards maybe they identified him (so he was a POI) but they didn't get the DNA back until recently. They might not have thought just his car on video was enough for probable cause. Or worried that a good lawyer could argue it's not enough and then he's out and he knows he's on his radar.
I struggle a bit because if they knew who he was, they know how dangerous he is: he killed 4 random people in one of the most gruesome ways possible! What if he was going to do it again? Don't they have a bit of a duty to take him in as soon as possible? The MSM so far seems to only say he was trailed for a few days. I wonder if they had him under surveillance for a long time and felt he was "contained" enough to not have the risk of this known dangerous person be free to kill again.
I hope this PCA contains enough evidence that we can learn about the investigative steps too.
I think they had the stranger DNA right away (maybe even by Monday morning). Surely by the time they announced that several people were "believed not to be involved," so by end of Week 1.
Because his DNA was not in CODIS and they needed a sample. They could not take samples of everyone in the region, so they focused on the Elantra - which clearly they have video of, coming and going on the night of the crime.
The Elantra led them to a criminology student in Pullman, who became a POI. They were likely watching him. I'm sure the BAU considered him to be no immediate risk (and he wasn't, they were right).
So they followed him to PA, and either went through the parents' trash or got a swipe of his DNA or his father's DNA or his mother's DNA from a car or a doorknob. Surreptitiously.
So they got a match to the DNA back at the crime scene. I think this is when Chief Fry got that noticeable twinkle in his eye.
Then, it's my understanding LE took about 4 days to plan how best to nab him with no one else dying.
I completely trust BAU and LE on this. He wasn't going to kill his own father. He went inside his parents' house and probably saw only his parents. He is not the kind of person who plots to kill his own parents and he didn't.
Chief Fry gave the exact reason. "We don't just want an arrest, we want a conviction."
BK is going to have a tough time wiggling out of the DNA evidence in this case. But they needed to match the crime scene DNA with someone and they can't just arrest BK for that reason. Having stranger DNA in a crime scene is not probable cause for arresting someone whose car was in the area. The subject was fleeing, yes, but in the company of a parent. And at winter break time. Perfectly normal behavior.
They needed the DNA match, full stop. He has no known connection to the people murdered. It's the link.
Not meant to disparage at all but what would attract BCK to WSU?
Grant, scholarship, cost? Isolated small town?
One of the few places that admitted him? Plus, it's in a lovely location. Isolated small town might be appealing (although nearby Moscow is even smaller). WSU has a student body almost 3X that of U of ID, IIRC.
BK's checkered academic past (including the time off for his apparent rehab and the fact that he's a late bloomer, graduating in Spring 2022 with a Master's at age 27-28 isn't typical, plus the school he graduated from is not a top 50 or even a top 100 school; and while his background is in psych and Criminal Justice (which is different from Criminology, but related) is in the ball park, he apparently has no actual experience working for, say, a law firm or a law enforcement agency or similar. His psych background is, apparently, community college and undergrad work.
His Master's thesis might have impressed them at WSU and his willingness to pay out of state tuition is probably a key reason he was admitted (typically, public universities get to keep the extra dollars from that).