If Bruckner’s number is in the files then why didn’t the PJ make more strenuous efforts to investigate him, or do sceptics believe it’s quite acceptable to rule suspects out on the strength of an unanswered knock on the door?
Unless I'm mistaken, OG did most of the plodwork in wading through phone numbers (I'm not sure whether the PJ ever went much beyond the McCanns, Murat and those associated with them).
I'm trying to verify if the Portuguese required ID to buy a pay-as-you-go number / SIM back then. If not, identifying the holders would have been difficult, if not impossible, unless it cross-referenced to someone.
Brueckner may or may not have been in the files, and even if he were, his phone number might not have been noted, or he could have changed it or had more than one.
What seems more likely to me is that the Germans got a tip-off, identifying him as the holder of the number, and then checked whether the number corresponded to one of the ones in the files.