Considering who she was detained with ("I soon found myself locked in a room with a pedophile, a woman smuggling $25,000 in cash and unsavory others"), they were right perhaps to not give her the initial benefit of the doubt.
Er, how Kafkaesque is that? They (or, rather, their coworkders) are the ones who detained her in the first place. "So, we locked you in this cell with these other unsavory people. Notice how now you're in a cell with unsavory people -- very suspicious!"
Sorry, that wasn't what I had meant at all. I meant that if they're used to dealing with people who are constantly working the system, why would they ever go into their job thinking positive thoughts about the people they're dealing with. If she is the exception, she will likely be considered nefarious until proven otherwise, they just don't usually give the chance to actually prove anything, otherwise or not.