"They don't have the manpower to take every case. It's about policy choices. You can't prosecute every case. You can't prosecute most cases. So you have to make choices to prosecute wisely," Mr. Gershman said.
Federal pension theft not always prosecuted →
Bennett Gershman, a former federal prosecutor and law professor at Pace University, said a host of factors come into consideration when deciding whether to file charges in any case.