First he was an executive. Then he was a cop. Now he’s a novelist.

First he was an executive. Then he was a cop. Now he’s a novelist.

Mark Johnson once walked the streets of downtown Mobile as a top executive of a prestigious nonprofit. Later, after a most unusual midlife career change, he patrolled the same streets as a 50-something rookie cop. On Friday he’ll be one of the attractions at the city’s monthly art walk, as a fledgling novelist.

Going through police academy training in late middle age was tough; Johnson made that plenty clear in “Apprehensions & Convictions,” a memoir he published about seven years ago. You’d think going from memoirist to novelist would be easier than going from executive to flatfoot, but Johnson isn’t so sure.

“I thought I would try it, but I had no idea it would take six years to complete it,” Johnson said of his new book, “Bad Day on the Bayou.” “And I don’t know if I would try it again, because that was just agony.”

Mark Johnson once served as head of the United Way in Mobile, then became a rookie police officer at 50. He drew on his 12 years on the force to write his first novel, “Bad Day on the Bayou.”Down & Out Books

Johnson will sign copies of the finished product at the Haunted Book Shop at 9 S. Joachim St. from 6-8 p.m. Friday. The event also will feature author Ocean Springs-based author Johnnie Bernhard signing her new thriller “Hannah and Ariela.”