“It is the job of thinking people,” Albert Camus once observed, “not to be on the side of the executioners.” But what are we to do when the executioner is himself a thinking person? Joel F. Harrington addresses this conundrum with remarkable skill in his fascinating exploration of the life and times of a 16th-century executioner named Frantz Schmidt, who practiced his “odious craft” for more than 40 years at Nuremberg, of all places.

“Professional killers like Frantz Schmidt have long been feared, despised, and even pitied, but rarely considered as genuine individuals, capable — or worthy — of being known to posterity,” Harrington tells us in the book’s opening pages, as Schmidt subjects a “penitent counterfeiter” to the prescribed punishment of being burned alive. “But what is going through the mind of this sixty-three-year-old veteran executioner as he brushes clean the stone where the convicted man’s last gasps of desperate piety so recently pierced the thickening smoke?”

The answers emerge from the pages of a journal that “Meister Frantz” kept throughout his long career, an unflinching record that begins in 1573, when Schmidt is a 19-year-old apprentice to his father, and goes on to record some 394 executions and hundreds of additional acts of flogging and other forms of torture. Harrington, a history professor at Vanderbilt University, brings a scholar’s eye to this challenging document, rigorously weighing Schmidt’s original version against the embellishments of later editions and teasing out insights in a manner that allows us to see “a thinking and feeling author step slowly from the shadows.” The result is a surprising wealth of detail, from the pungent “wafts of vomit and urine” that anticipate the counterfeiter’s execution to the moment when Schmidt adorns the condemned man with pitch and gunpowder to accelerate the body’s burning and arranges to strangle him “discreetly” with a silk cord, sparing him the agony of the flames.

Schmidt’s job, Harrington explains, was to provide a “good death,” playing a lead role in a grisly pageant intended to shock the locals and confirm the established order. “The court condemnation, the death procession, and the execution itself constituted three acts in a carefully choreographed morality play,” Harrington says. Schmidt’s role in the drama required him to administer death in many forms — hanging, burning, decapitation and even execution with the wheel, which required him to deliver a court-mandated number of blows with a heavy wagon wheel. If the court had been merciful, Schmidt would administer an initial “blow of mercy” to the condemned man’s neck or heart, putting him out of his misery before shattering the limbs of the corpse. If the court had been in a vengeful mood, Schmidt proceeded “from the bottom up.”

Many will find it surprising that this professional killer also did a brisk business as a medical man. It was not uncommon, Harrington explains, for an executioner to acquire a significant knowledge of human anatomy as a natural consequence of meting out torture and court-prescribed mutilations, such as tearing out a blasphemer’s tongue or chopping off a gambler’s fingers. Like many of his fellow executioners, Schmidt became skilled at setting broken bones and applying healing herbs and salves to the condemned, so as to keep them alive long enough to ascend the gallows. Schmidt emerged as a respected healer who plied his skills among law-abiding citizens as well as convicts, and in time his fees from medicine exceeded his executioner’s salary. Harrington estimates that Schmidt treated as many as 300 patients a year, roughly 10 times as many as he dealt with as an executioner. “Undoubtedly his widespread reputation as a successful healer helped mitigate the disdain normally reserved for executioners,” Harrington writes. “But it was not enough in itself to make him or his family honorable.”

‘The Faithful Executioner: Life and Death, Honor and Shame in the Turbulent Sixteenth Century’ by Joel Harrington (FSG)

The question of Schmidt’s family honor, at a time when the executioner’s profession was officially designated as “dishonorable,” is perhaps the most compelling thread of Harrington’s narrative. Schmidt came to the job through his father, an “innocent woodsman” who had been all but shanghaied into the post by an unscrupulous nobleman. Harrington details the dogged manner in which the younger Schmidt, while dutifully carrying out his obligations, pursues a lifelong endeavor of restoring his family’s good name. Finally, having retired after more than four decades of service, the 70-year-old Schmidt mounts a successful appeal to the emperor, Ferdinand II, “defying his fate” against seemingly insurmountable odds. “He had achieved his goal,” Harrington writes, and spared his sons the stigma he had known all his life. “It was not the executioner’s sword that he would pass on to them but the physician’s scalpel.”

In the end, this is a surprisingly modern, even topical story that poses difficult questions about capital punishment and what Harrington calls “the human drive toward retribution.” Although Harrington resists moralizing for the most part, many readers will feel an uncomfortable jolt when he notes in a parenthetical aside that one of Schmidt’s torture techniques is “today known as waterboarding.”

“It would perhaps be pleasant,” Baudelaire once remarked, “to be alternately victim and executioner.” It’s doubtful that Schmidt would have agreed, but his story adds a great deal to the conversation.

Daniel Stashower is the author of “The Hour of Peril: The Secret Plot to Murder Lincoln Before the Civil War.”

THE FAITHFUL EXECUTIONER

Life and Death, Honor and Shame in the Turbulent Sixteenth Century

By Joel F. Harrington

Farrar Straus Giroux. 283 pp. $28