You do realize, don't you, that it takes about 14 hours to drive from Hamilton, Alabama, to Boulder, CO. (That's non-stop--no breaks, no gas fillups).
It would have been physically impossible for John Karr to get to Boulder by 5 P.M. on Christmas Day, to hide under JonBenet's bed (as he claims) and to murder her sometime between 10 p.m. and midnight.
Not if he didn't drive.
Closer to 19 hours and what's more, it snowed that night over Raton Pass and in the Denver area including Boulder. While the snow melted later in the day, the night before the slick spots slowed travel down significantly. I know. I traveled to Boulder that night from Florida and arrived just prior to sun-up.