Question - Paychecks Kept Coming.

Ken, a salaried employee, was terminated from his company in April of this year. Business had been slow since the beginning of the year, and each of the operating plants had laid off workers. Ken's dismissal was processed through the Human Resources Department, but the information was not relayed to the corporate payroll office. As had been the policy, checks for workers at remote sites were mailed to the employees. The mailing of Ken's checks continued for the next four weekly paydays. It wasn't until the monthly payroll reports were sent to Ken's supervisor that the error was detected. Ken refused to return the four extra checks. What actions should the company take?