Spotting internal fraud
This is one where unfortunately I can speak from experience. There are some normally honest people who will rip you off out of opportunity, and some broken people who scam you because if they can you deserve it or will do so because they beleive their own bullshit and thus think they are entitled to what ever they can take. Most horrifically these people can also seem like the nicest most credible people who you may think could never do such a think. Take my warning and just treat everyone as capable and put controls to remove the easy opportunities for your trust to be betrayed.