An old-school graffiti artist was busted for leaving his “RD” tag all over the East Side of Manhattan — and it turns out he works for the city, cops said Friday.

Robert Dyer, 49, who works for the New York City Department of Health and Mental Hygiene, was arrested Wednesday and charged with 82 counts of making graffiti.

The bust concluded a 6-month investigation to track down the vandal.

The retro writer has 13 prior arrests dating to 1982 — when he was just 15 years old.

This time, Dyer was caught with a paint marker in his pocket.

He is due back in court Sept. 20.