Al Capone was never convicted of being a mobster; much less of being the head of the mob, Al Capone was convicted of tax evasion. Money makes the world go 'round so it would follow that money related crimes are more prevalent than others are, and they are. In fact, the Bureau of Labor Statistics lists accounting as occupation 001! There would have to be a law enforcement component devoted to accounting and there are, many. The image of the be-spectacled, bean counter fades away when you realize that the FBI hires more accountants and most corporations. In fact, one of the surest ways to get into the FBI is by having a degree in accounting. Moreover, nothing is scarier than the IRS. So before you discount a career as a "Be-spectacled, bean-counter" consider becoming a Forensic Accountant.
The first step is to earn your CPA. While you can jump right in to the field of accounting in general by seeking employment at one of the many tax preparation services and getting your CPA, online for example, while working, you might want to consider more. A full bachelor’s degree would be better for your career aspirations. There is a lot to learn and the field is still being defined. There are few actual, recognized certifications in the field. This means that you will be expected to learn a wide range of specialized skills as well as law enforcement related subjects as well. Your knowledge of computers, software and network systems will need to be top rate as well. Yes you can "get your feet wet" quickly but you will need to really plan your education well to be successful in forensic accounting.