I want to report someone to uk border agency who has got citizenship recently, however they gave false info?

i know someone who was granted B citizenship 2 weeks back, and they are awaiting the ceremony date, how i know that they have been giving false information from the start , saying they are someone who they are not , that they are in danger in there own country how ever they are not., also when they first came to england illegally few years back they were allowed to stay but the Information they gave to the uk border agency was false and . i am wondering how to i go about reporting this person. ? i have emailed the police , and they said i should get in touch with public enquiries uk border agency, i have done that but i have not heard anything as yet? so i wondering if i have emailed the right people can anyone help?