He's just a beat cop man. His job isn't to investigate, just to take the statement. As he said, the statement will go to the investigator. It's not like every cop with a badge is a member of SVU out there to trap criminals.
Issue tickets and take statements. The rest of it filters up the chain from there. You could call the dept and ask if an investigator has been assigned.
Not that I'm some kind of expert - I just play one on the internet. Understand your frustration and hope you get justice.