I believe all of the law schools in the area (American, GW, Georgetown, Catholic, Howard, UDC) all have night programs. GMU in Arlington and the law schools in Baltimore also have night programs.
That said, I think that you will find law school time consuming, expensive, and boring because you'll need to take non-criminal law courses if you plan to take the courses toward a degree. But contact
https://www.pdsdc.org/ and see how you could volunteer in a non-attorney capacity. Attorneys need paralegals, investigators, and anyone who is good at research and writing. As long as you are working under the supervision of a licensed attorney, you might be able to do some really interesting work.