If I recall correctly the Howard County Police department is responsible for law enforcement in Columbia (they were in 1972 anyway). The law enforcement agency certainly has a procedure for filing a complaint.
From my experience in law enforcement all complaints were investigated by the professional standards division and the complainant was notified of the result of the investigation.
I was a deputy sheriff for 11 years and I wouldn't hesitate to make a complaint about the way this was handled. It's cops like that who give all law enforcement a bad name. The investigators I worked with in Colorado would have never treated a citizen like that. It was unheard of.