Why not take the LD test? That is certainly a way for Kate put alot of negative thoughts about her to rest. You were right, both Walsh and Klass took LDT. IIRC, Klass begged to take one.
We certainly have an inkling why Kate won't take the test, right?
And, by the way, the detective that says Madeline is still alive was hired by the McCanns. The detective is not stupid; he doesn't want to cut his own funding.