Often times, it's not like the movies where there is some evil purpose. It's more likely that they break the law in a good-hearted attempt to do their job. Or, it's just ordinary theft. It's often stupid reasons.

Anybody in government should be aware that there's always a record of what they are doing. There's always a paper trail. The fact that they get away with crime for so long is mostly due to nobody suspecting and then investigating. It's usually during audits that people get caught. And even then, audits only sample records, so it may be a few audits before they uncover the problem.