Kehoe was a Michigan farmer who became disgruntled after losing reelection as treasurer of the Bath Township school board.

There, he first met his future wife, Ellen "Nellie" Price, the daughter of a wealthy Lansing family.

[9]: 28 Kehoe was regarded by his neighbors as a highly intelligent man who grew impatient and angry with those who disagreed with him.

Neighbors recalled that Kehoe was always neat, dressed meticulously, and was known to change his shirt at midday or whenever it became even slightly dirty.

[14]Recent analysis identifies Kehoe by the term "dangerous injustice collector”: a person who remembers slights and holds a grudge for a long time.

Another neighbor, A. McMullen, noticed that Kehoe stopped working altogether on his farm in his last year, and thought he might be planning suicide.

[14] During these years, Nellie Kehoe was chronically ill with tuberculosis, and had frequent hospital stays—at the time there was no effective treatment or cure for the disease.

By the time of the Bath School disaster, Kehoe had ceased making mortgage and homeowner's insurance payments.

Kehoe had set a timed detonator to ignite dynamite and hundreds of pounds of pyrotol at the school, which he had secretly bought and planted in the basement of both wings over the course of many months.

[20] During the rescue efforts, searchers discovered the additional 500 pounds (230 kg) of unexploded dynamite and pyrotol planted throughout the basement of the school's south wing.

After the bombings, investigators found a wooden sign wired to the farm's fence with Kehoe's last message, "Criminals are made, not born," stenciled on it.

One of Kehoe's sisters claimed his remains and arranged for burial without ceremony in an unmarked grave at Mount Rest Cemetery in St. Johns, Michigan.