I was a licensed private investigator. I did that from age 50 to 55. I was very good at it. The agency that hired me said a woman my age would be under-estimated. They liked my skills at interviewing (which I'd used as a freelance writer). I worked a lot of cases for the defense in criminal trials and a couple of corporate cases.

I left because the hours were crazy, and I had a new job making more money as a home school teacher. (grin)