I’m pretty sure the correct release date for this is 1978.
I've noticed that MC sometimes shows the date of US release rather than the date of first release. Maybe that's it?
I looked it up on IMDb and by the title it does list the date as 1978, but if you scroll down in the release notes it states 1985 as the West German release date.
You are probably right. Curti’s Italian Crime Filmography 68-80 only has the one Italian release date of December 1978. I can’t find much else on it.
It's weird. You'd think MC would carry the date straight over from IMDb, but I've seen this happen on quite a few non-US movies.