Jacobi was always a writer; at his junior high school he earned good pocket-money concocting his own 'dime novels' (short story booklets) and selling them to fellow students as 10 cents-a-piece.

[1] Jacobi attended the University of Minnesota from 1927 to 1930, majoring in English Literature, where he began his writing career in campus magazines and was an undergraduate classmate of Donald Wandrei.

After a while regular hours palled, and he left the Star, renting an office in uptown Minneapolis in which were typewriter, paper, a few reference books, and a list of editorial addresses in New York.

[4] Jack Adrian writes: In the depression years of the early 1930s, the pulp-writer needed as formidable a creative armoury as possible, along with a certain amount of luck, and cunning, to crack even the lowest paying markets.

Jacobi had a useful knack for dreaming up memorable milieu against which to set his tales, and bizarre situations that stayed in the mind long after the magazine the story itself was in had been finished and tossed away.

This was "Revelations in Black", a chilling, and much-reprinted, vampire tale set in an old stone farmhouse outside of Minneapolis Jacobi had driven past one night (the house's eerie statue-lined garden, as seen by brilliant moonlight, had caught his eye and his imagination.

Pressed by financial problems and the need to help his parents survive the Depression, he took a $50 a week job as a continuity writer for the local radio station where he stayed until 1940.

Jacobi wrote to officials working in Southeast Asia to obtain details for his stories,[5] and he had considerable knowledge of that background in his fiction.

According to Jack Adrian, "He would write to those in charge of far-flung outposts deep in the heart of the Borneo jungle, say, demanding geographical detail, obscure ethnic lore, atmospheric and forestall conditions; anything, in short, you couldn't get out of a book.

This way he became an acknowledged expert in a field he had created himself, at the same time inventing whole new fiction subgenres, such as "Borneo terror tale", "New Guinea adventure" and so on.

At this time, Jacobi listed his hobbies as "studying the night sky with a 60 power glass; continuing contacts with friends now located in jumping off spots of the South Seas and Malaysia; and collecting old tobacco tins.

When the pulp markets collapsed, Jacobi took regular employment with one of the Honeywell defense plants as an electronics inspector, a job he had through WWII and beyond, while writing part-time.

He worked the night shift at Honeywell seven days a week, which had a severe effect on both his writing schedule and his health, leading to heart problems.

[citation needed] 1964 saw the publication of Jacobi's second collection of weird fiction, Portraits in Moonlight, and several short stories published in magazines.

In the same year, Etchings and Odysseys magazine was launched in Minneapolis by Kirby McCauley, John Koblas, Eric Carlson, Joe West and others.

[3] Debilitating illness crippled Jacobi during the final half-decade of his life, although his literary agent and biographer R. Dixon Smith did much to alleviate his various afflictions.

Fritz Leiber wrote about Jacobi: "his best tales surely include "Mive", "Carnaby's Fish", "Revelations in Black", "Moss Island", "Portrait in Moonlight", "The Lo Prello Paper", "The Aquarium", "The Singleton Barrier"...and "The Unpleasantness at Carver House".