The relation between an employer and employee is fiduciary in nature and also depends on trust. The very appointment letter obtained through suppressing the facts even after making declaration that all your submission were true to the best of your knowledge make your employment vicious. In police verification, the police will not suppress the facts since all the queries are matter of records which can not be altered later on even if you purchase the police personnel to write in your favour. The best way is to get a post facto permission from your department but they are also not bound to give it until you have good relation with your boss. However, the entire things depend upon the terms and conditions written in your application form where you work presently and the new employee who is going to appoint you. However, mind it that the fruit if a poisonous tree is always poisonous.Job obtained by violating the service code is a misconduct. Your new employer would never like that the new employee should obtain the job by a deceitful means.