Whether the prosecutor could refuse to enter into the criminal complaint without further investigation
No. The complaint was understandable and described facts that could potentially constitute fraud, so an instruction had to be opened.
The facts alleged suggested a possible fraud scheme under Art. 146 CP. The potential injured parties were both the tenant and the municipality. The prosecutor had to examine the matter ex officio and should not have refused entry solely because the complaint was not further substantiated within the given deadline.