MVC3,Entity framework,webservice,database

I run an interface every day which updates the data in database if the record is present of that employee or else inserts in database if employee is new. My requirement is to check if there's any employee who is no longer coming in that interface. The basic method is after getting response from interface i need to make a call to database to bring all employees present in my database and check the response from interface to find which employee is not coming now in interface. Is there any better method?