If you have the chance to go back to school, DO IT!!
With regards to your criminal/law degree interest, there are a few options you could do. You could get your degree in criminal justice and become a LEO. Or you could then go on to law school. I would stay away from the pre-law program though. You may find later down the road that law is just not your thing, and then your stuck with limited options with your pre-law. You should get your degree in something that has many options for jobs. For example, get your degree in accounting. This field has MANY options out there. With that degree, you can still get a job as a LEO. In fact, I have a friend from college that did just that. You can still go to law school and specialize in fraud accounting/white collar crime/business litigation/tax attoney/divorce attoney/ect.ect.... There are TONS of options in law that an accounting degree would be great for. If you then decide that law is not your thing, then you still have many doors left unopened with an accounting degree. You could work in public accounting,PWC, Deloitte, KPMG, BDO, ect..... Or the private sector has millions of options for jobs. Better yet, open your own cigar shop with your acc. degree. Obviously accounting may not be your thing, but still pick something that you can have options with and that you can still become a LEO with or move onto law school with. Just my 2 cents, but I hope this helps a little bit.