In other words they'd been investigating this suspect for three years when they decided to ask the public for help. Another year has passed and they still haven't got enough to charge him. It's not looking promising imo.
No they did not "decide to ask the public for help".
Amaral leaked sufficient evidence to flag up the German paedophile in a German jail. Flamin' press!!! they can't get nothin' right. Amaral had to break his cover again and point them in the right direction to a German paedophile in a German jail that no-one but the investigators even knew his name.
He worked really really hard at trying to blow the German case into oblivion.
I suggest that without the Amaral interventions it is perfectly possible that Brueckner's name still wouldn't be in the public domain and the investigation into him and perhaps others would be proceeding without notoriety.
I think the investigation made the best of a bad job and asked the public to fill any gaps in their knowledge.
In the interim any who had hard drives or storage devices which might have contained evidence had been flagged up that it might be time to get them sorted out.
If Madeleine is alive somewhere she won't be in that location when the investigators reach it.
I think Goncalo Amaral and his paranoia caused disruption in 2007. But not nearly as much as he did in 2019 when he broke cover on Saunokonoko's entertainment show in the attempt to wreck the German investigation.
Do you never ask yourself the question of why on earth did he do that?