Constitutionally, the chief law enforcement officer of any state is that state's attorney general. The present Illinois Attorney General (2011) is Lisa Madigan.
The state legislatures with the approval of the governor make the laws, but some townships, cities and counties make additional local laws.
The Sheriff
The chief law enforcement officer of California is the state attorney general, currently Kamala Harris.
No. Police officer is not a proper noun
In most counties the Sheriff or District Attorney is the chief law enforcement officer for the county. In most states the State Attorney General is the chief law enforcement officer for the state.
the sherif
The County Sheriff
the sherif
District Attorney
Any law enforcement officer with an arrest warrant. The chief law enforcement officer for the county is the county prosecuting attorney (DA)
You would call him/her the chief of police.
In the United States, each county elects a "Sheriff". The Sheriff is the chief law enforcement officer of the county, and is also responsible for the carrying out of court orders and county tax codes. The Sheriff delegates his (or her) power to the "Sheriff's Office" (which is similar to a police department).
Law enforcement Officer.