Has Nygren abandoned the Office of Sheriff?

When an elected official is seldom (or never) in his office, can that mean that he has abandoned the office?

Can an elected official just take off and leave an employee in charge? And who is in charge when that employee leaves town?

Must the elected official - the person elected by voters to run the office - designate the person to be in charge when the assigned employee is out-of-town or otherwise not available? Just so that you don't get confused here, I'm referring to Sheriff Keith Nygren (elected) and Undersheriff Andy Zinke ("assigned employee".

The current rumor is that Nygren has taken up permanent residence in Florida. And I hear that employees of the McHenry County Sheriff's Department are not supposed to be asking, "Where's the boss?"

What makes a person a "resident"?

Intent to become a resident is one factor.
Getting a driver's license is another factor.
Registering to vote in another state is another factor.
Not maintaining a legitimate residence in the County where he was elected, is another factor.
Just renting a place for a bed in the County might not be enough to avoid losing the residency required to continue to hold the office.

Who should investigate whether Nygren has abandoned the office?

The County Clerk?
The County Board?
The State's Attorney?
The Illinois Attorney General?
The FBI?

And where is the MCSD vehicle assigned to the Sheriff? If the mileage records for the past four years were requested by FOIA, what pattern would those records reveal?