Sachithra, There are thousands of illegal workers in Qatar. Are you going to make a complaint against all of them? You have no right to complain about an illegal worker in your company. If he is an illegal worker in your company it is the responsibility of your HR or Personnel Department to check. Why did they allow him to work there if he is an illegal worker. If he is caught your company will also get a fine and will have problems from the Immigration Dept. Do you have any personal grudge against that person? If not why you are so eager to act on such issues?