I agree with others that he will not take the stand in his own defense. So, aside from his testimony, what do you think he can introduce to prove these points?
He would have to prove he was there, btw. There's phone ping evidence that he was there in the neighborhood in the middle of the night, there are multiple cameras that caught him driving right up to the driveway of 1122 just before the burglary/murders occurred. He then speeds away (on camera) right after the time of the murders.
So it's not just pings. LE now has way more evidence, namely:
- Evidence from his car
- Evidence from his apartment
- Evidence from his parents' house
- Evidence from his parents' neighbors' trash
- An exact DNA match (from his own DNA swabbed at arrest time)
- Records from all devices he used (FBI can restore a lot of deleted data on phones and computers)
- Records from Google regarding searches made by his phone and his computer (by device identifiers)
- GPS records from his phone; he likely used Google Maps
- Records from other social media sites documenting whether BK is actually Pappa Rodger, InsideLooking and TapaTalk guy (or showing that he is NOT that person)
- His DNA, now that it is plainly known, will be easier to find on other items than just the sheath
- Fiber analysis from the crime scene, particularly regarding latent fibers from a 2015 Elantra
- More latent footprints and visible footprints (obviously, as it's highly unlikely he hopped from place to place on one foot inside the house)
- Receipts and records of his clothing purchases, any other relevant purposes (they'll eventually get the Albertson's receipts, IMO)
- Evidence of cleaning car immediately after crime
- Possible pictures of him wearing Van's pre-murder and not possessing them any longer (every bit of surveillance video of this man will be collected - and is being collected at the current time; also some of his colleagues may have noticed his shoes; they are being trained to be observers, after all.
Further, there are people who are able to report on his behavior pre- and post-murders.
There's camera evidence of him leaving Pullman and arriving Moscow at just before the time of the murders - in the wee hours of the morning.
No other DNA has been reported as found on that sheath, so it's very hard to explain how 4 people were murdered with a knife that goes into that particular sheath (Ka-Bar USMC), with the sheath found right next to one of the murder victims and the only DNA on the sheath is BK's. I assume that the amount of DNA found on the sheath confirms more than one "touch" is fairly plentiful, even though they likely have not tested the whole knife yet (they need to allow the defense to test it too).
IOW, there's a lot more to come. His defense has a major uphill battle. I don't recall another case that poses as many difficulties for the defense as this one - and I"m sure I've totally forgotten some vectors of evidence.