I had a thought early on in the case, which I never bothered to discuss, but lately I have been thinking it again.
What if LE had a suspect immediately? Releasing a couple of blurry stills from the video may have been their way of showing the suspect enough evidence to try to get him to turn himself in. I remember they kept saying things like they were waiting for one tip, a specific tip, that would solve the case... and that in alllll those tips they knew it hadn't been called in yet. As least that is about what I remember hearing, and the only way I can get that to make any sense is with this theory.