A number of citizenship processes require a certificate of good conduct that one does not have a criminal record in another country. Within the US this is generally an FBI Identify and History Summary Check (IdHSC). One can have the FBI IdHSC within a day, it is not a complex process.
One starts by applying at the FBI IdHSC page and you get back a file number immediately. You give the file number to the Post Office when they take your fingerprints. Not all US Post Offices have the needed equipment, check at the USPS IdentityCapture page to find the nearest office which does. The post office charges $50 to take the fingerprints, but submits them digitally and you get the result in an email from the FBI within hours.
We printed the PDF file we received from the FBI to mail to the Bundesverwaltungsamt (BVA) in Germany. It does not need Apostille.
In terms of timelines: we got a request for the FBI clearances when the caseworker began looking at our file. The letter with our FBI papers arrived in Köln Oct 10, 2023, the BVA accepted the declaration November 15, 2023. The Consulate informed us that they had the Urkunde ready for pickup Nov 29, 2023.
