I'm not 100% sure about this, although this is a first-hand story of an ex-classmate from Russia (so, caucasian, blond, etc..). She was asked for her Ausweis somewhere in Bern, which of course she didn't carry with her at that time. The police officer/s actually took her to their post where she had to wait until her husband could bring her Ausweis & show it to the police.
This happened at the wee hours.. (about 3am, just when the Ausgang places/bars are closing & she was on her way home..)