We don't know.
There are suspected links to the OKC bombing.
The "19th hijacker", Mousaui. was there awhile. He even crossed paths with Nick Berg (using his computer account). Odd for a wandering college student who would later wind up captured and decapitated in Iraq.
Now another Norman OK death.
There are some suspicious activities there (often linked to the same Islamic center) but no conclusions.
We don't have all the pieces the authorities do.
After the first Gulf War, they settled a lot of Iraqi Republican Guard who had defected or became captured in OKC and within a short time some of these people became very anti-American. This is called the Heartland of the Country and thus they set up shop in the Heartland.
A professor told a friend of my daughter's that there are three active cells in OK -- Norman, OKC, and Tulsa.
it was a rhetorical question.