The reality is he is building a case, take at face value if needed. I think we all do here. Will he be tried in portugal or germany? If charged, however do you think its rational and realistic that a foreign police force would spend time and money if they did not think their was something their. Op grange still has not released their files of certain things, a foreign police force certainly wont waste time on a foreign citizen in a different foreign country if they did not believe connections were there.
Wolters has been building a case since 2017, apparently, but not just the Maddie case is it, Brueckner is a long term criminal, they've been investigating him for multiple crimes, but, the best they can pin on him are Hazel Behan & playground molestations. Not the Maddie case, they have 100% convincing concrete evidence & absolutely no doubt whatsoever that Brueckner murdered Maddie, but can't see him being charged with murdering Maddie anytime in the future. He's been sat in a cell for years so his crime spree has now halted.
His name has been splashed across mass media for the past two years, so barring criminals, anyone who had any information on him would likely have told the police by now.
Maybe they need a bit more time then & something will turn up, maybe they'll be able to link him to other crimes, there's nothing at the moment though is there.
The MET have been given a further 12 months funding for their investigation into Madeleine's disappearance, which is strange, considering it should be a murder investigation by now, maybe Wolters hasn't shared the concrete evidence with them. Maybe the MET, or the PJ will find the elusive final piece of evidence Wolters is lacking, even though he doesn't really need it, since he already has conclusive proof Brueckner murdered Maddie.