In my way of thinking if "it has been solved" they don't really need any more evidence, so I don't understand your comment Sadie.
In order to prosecute a very elite man with a globally well respected organisation behind him, they need substantial undeniable evidence.
I believe Madeleine was abducted to order. That the master abductor commissioned others to do his dirty work. Very probably the actual physical abductors do not even know who the master is.
I believe Madeleine was abducted and taken up to Porto in at least three different stages. Each stage only having contact with the stage above and below them.
I believe that SY have some very strong reasons for thinking they know the master abductor.
Maybe they also know the actual physical abductors, but have they found the people in between? Difficult to prove anything without them
Everything compartmentalized so the bottom guys have no idea who the top guy is.