For this type of case, the SPF will normally classify it as civil case. The reason is very simple. By doing so, they need not take any further action. Furthermore, it looks very nice statistically. Very low crimes rate.
The police force in singapore is run by civil servants, who are paid handsomely but have no ideas on what to do with scammers, who use intimidation to cheat and scam locals and tourists openly. Creating false invoices to scam is cheating but the foot patrol mata mata is as blur as the sotong if the top man in the police force is super blur.