What I found interesting, from the book, was the whole idea that the defense was faced with insurmountable evidence, and figured their only hope was to suggest a wildly different theory of the crime. It was the idea that they knew contesting the evidence, item by item, was doomed to failure. Even though it is a work of fiction, when their private detective set out to poke holes in the husband's alibi, the only expectation was to raise some doubt - to create the specter of a "person or persons" unknown.
If the sexual assault DNA doesn't get explained, then it seems the defense, in this case, is most of the way there.
