You don’t need to hack into a computer to learn about someone. Today, most people that I investigate leave a revealing online profile — I just have to connect the dots or the publicly available dox (documents).
Online malefactors try to do their misdeeds anonymously through an alias. Usually, they tend to reuse their aliases. It only takes one obscure use connected to the miscreant’s real name. Now I have the real name to run through the usual searches which will reveal other aliases, Facebook pages, and Twitter accounts, all of which yield titbits of useful information.