Criminal registers for that period are available on Ancestry. Using location as Cambridgeshire 1867-1871 does not show any entry for that name but there are 15 entries where initial were J S - Smith mainly but also other surnames beginning with S
Possibly not tried in Cambridge
Oh, I didn't know it was possible to do a wildcard search in Ancestry to find people with the initials JS. That's very useful to know. Thank you.
I've just done a search of the criminal registers on Ancestry for Cambridgeshire, 1867–71, and got 18 hits, none with a German-looking name. However they all seem to be records from the quarter sessions. I can't see anything from either the assizes or the petty sessions. I imagine cases at the assizes were rare enough that they're unlikely to be relevant here, but what about the petty sessions? I assume justices of the peace had the power to imprison someone, as magistrates do today. Are there likely to be any surviving records for the petty sessions?