afaik, sergeant first class is a miltary rank, not a police rank in the US.

Police
The rank of Sergeant or its equivalent is common to the police of many countries. In the British police, Sergeant is senior to Police Constable and junior to Inspector. In most American police departments, Sergeant is the rank junior to Lieutenant. Many police forces also use the rank of Corporal. In the Irish Garda Síochána, Sergeant is senior to Garda and junior to Inspector. The New Zealand Police, and Australian police services, also have the rank of Senior Sergeant. Police sergeant is usually the highest rank which performs direct field supervision.
http://en.wikipedia.org/wiki/Sergeant

--------------------------------------------------
Note added at 33 mins (2006-03-27 21:24:28 GMT)
--------------------------------------------------

police sergeant may be enough. US is confusing since it's a state by state thing.

--------------------------------------------------
Note added at 37 mins (2006-03-27 21:28:13 GMT)
--------------------------------------------------

POSITION TITLE
POSITION TITLE: SENIOR POLICE SERGEANT. GENERAL DESCRIPTION OF DUTIES. Under direction, the purpose of the position is to perform supervisory and general ...
www.town.herndon.va.us/Job Descriptions/sr police sgt.htm

[PDF] Regular Minutes City Council/Redevelopment Agency City of ...
File Format: PDF/Adobe Acrobat - View as HTML
Employees in the Classifications of Police Sergeant and Senior Police Sergeant from the Police. Management Association to the Huntington Beach Police ...
www.ci.huntington-beach.ca.us/files/users/city_clerk/091905...