There was absolutely no way that the German Prosecutor, was ever going to find anything at the Reservoir site, which could help prove, Christian B was responsible for Madeleines disappearance.
The man enjoyed visiting the Reservoir area apparently, so what, what does that mean?
As for the allegation that police tracked his mobile phone, and apparently a call was made on his mobile from very near the Ocean Club Resort, many questions to be asked about that allegation.
https://www.thesun.co.uk/news/22805561/madeleine-mccann-cops-major-blow-results-algarve-dam-search/