Hello again

I would like to ask another question, but it is not related to this thread and maybe you could help me again. My uncle who lives and work in UK migrated actually from Spain last 2009. Now, my auntie (his wife) would like to know anything about him (if he is living with someone, beneficiary, how we was able to get there, and etc) because she felt that there is something fishy about my uncle. So what government agency would we go to know about these information?

Thanks