Whatever your opinion of Yvonne Martin she made statements which count as evidence just as other statements do.
One witness statement was communicated in an anonymous letter of the green ink variety. Not once did this "Child Protection" individual concern herself with the children accompanying the persons she insidiously suggested might be capable of the most heinous crimes imaginable.
Without benefit of referral or inter-agency cooperation this loose cannon forced herself into a situation about which she knew nothing and no-one had the slightest idea of who she was.
Would she have dared to invade a police investigation in any country other than Portugal by latching herself behind an official vehicle and entering an area which should have been behind a police cordon if it wasn't already.
Martin did exactly what a competent professional is trained not to do resulting in freaking out an already distraught woman who nonetheless recognised and was alarmed by the inappropriate and voyeuristic approach of her self appointed interrogator.
Indeed I would go so far as to say her conduct is probably unprecedented by anyone who do not suffer from mental health problems.
She should never have been allowed near Kate McCann.
Her so called 'witness' statements to a situation she engendered without any proper background knowledge or investigation would be treated with the contempt deserved in any competent professional environment.