It's seriously NOT as up-in-the-air as one might think. BK's DNA is next to 2 mutilated victims, on a weapon accessory. His phone is awake in the middle of the night, roaming, pinging towers on a circular route around the murder house. His car is photographed on that same route, in the middle of the night. (Any sane person would be in bed, with phone pinging home towers only, and no photographs of his car in the middle of the night.)

There's digital evidence of BK pestering 1 or more victims on social media.

There are eyewitnesses of him wearing gloves everywhere after the murders. His WSU students say he stopped giving feedback or doing any grading after the murders.

There's an eyewitness who saw his figure type & facial features IN THE HOUSE WHEN THE 4 WERE SLAUGHTERED. The eyewitness timeline is corroborated by audio from external cameras, AND by video of a car (matching his).

Receipts for clothes that match the eyewitness observations were found in BK's Pullman residents. Clothes that match the receipts & match the eyewitness observations were found in his parents' house with BK.

STOP TRYING TO PRETEND THERE'S REASONABLE DOUBT. A reasonable person could explain 1 of these or 2 of these, but nobody can give a sane explanation for the cumulative mountain of evidence. The police got the right killer.