I reported a business for hiring illegal immigrants but they said the investigation could take months why?

i reported this business anonymously not giving them my name and phone number my boyfriend use to work there i have reported them in the past too, but a different agency and the place was found with many illegal immigrants employed there that have been deported. i gave them every detail i could possibly remember giving them the business's name, address, and phone number (which i don't know why they need the company's number do you?) but i'm worried they might not find anything wrong this time since they have been caught before and will i get into trouble if so if i did not give my name ect, i know they hire illegal immigrants and how come it's gonna take the U.S homeland security months too investigate it?