If they can place him there and he has given information only the killer could know, they can get him even with inconclusive DNA. Conversely if the DNA matches, they don't need anything else.
I can also garauntee you that cold cases all over the country from the 1996-2001 time frame are being looked at, and Boulder,CO PD is probably being inundated with DNA result requests.
What if the DNA matches, and it is conclusively proven he was NOT in Colorado in the December 1996?
(Other than setting the conspiracy theorists into a frenzy, that is)