How should I structure my email to my background investigator?

Should it just be barebones info EX: “hello this is ——-. I wanted to follow up with you in regard to my needed polygraph exam. Met with you in late November. Thank you” or do I give a more in depth email with what I’ve been doing in the meantime to aid me in my future career? I’m trying to think of a polite way to mention my need for a polygraph without it coming across as demanding. Thank you.