First, this is a terrible story and I do not condone killing anyone. The loss of four young college students is tragic. Second, I've been seeing lots of posts online (facebook groups, true crime subreddits, etc.) of people identifying the errors BK made that led to his arrest, and some have even suggested ways the suspect could have completed the murders without being arrested. Third, LetsRun is a running forum, so I will do my best to get this thread back to the topic of running.
It seems to me that BK was arrested largely because he kept driving to the area of the murders in his own car, and also used his cell phone in a way that suggested he was the killer (that + DNA evidence = arrest).
This BK guy was allegedly a runner. Pullman is like 9 miles from Moscow. That's a recovery jog for anyone running 70+ mpw. If BK wanted to complete the "perfect crime," then he should have left his phone and car at his apartment, jogged to the scene of the crime, committed the crimes, and then ran either a threshold or fartlek session on the way back (for an 18 mile day all before 6AM).