You've already got two different stories about Christmas coming from his ex-wife and his brother. If the DNA matches, case closed. If it doesn't, then that may or may not exonerate him.
they must have evidence placing him in Boulder that night. if he was living someplace else at the time, they need to show he traveled to Boulder.
otherwise, what is the DA going to say? that's he's some kind of houdini who can be beamed into another state?