Colonel James S. Ketchum dreamed of war without killing. He joined the Army in 1956 and left it in 1976, and in that time he did not fight in Vietnam; he did not invade the Bay of Pigs; he did not guard Western Europe with tanks, or help build nuclear launch sites beneath the Arctic ice. Instead, he became the military’s leading expert in a secret Cold War experiment: to fight enemies with clouds of psychochemicals that temporarily incapacitate the mind—causing, in the words of one ranking officer, a “selective malfunctioning of the human machine.” For nearly a decade, Ketchum, a psychiatrist, went about his work in the belief that chemicals are more humane instruments of warfare than bullets and shrapnel—or, at least, he told himself such things. To achieve his dream, he worked tirelessly at a secluded Army research facility, testing chemical weapons on hundreds of healthy soldiers, and thinking all along that he was doing good.

At an Army research facility, a soldier given a powerful mind-altering drug said, “I feel like my life is not worth a nickel here.” Photographs by Stills from “The Longest Weekend” / US Army Chemical Research & Development Laboratories / Courtesy James Ketchum

Today, Ketchum is eighty-one years old, and the facility where he worked, Edgewood Arsenal, is a crumbling assemblage of buildings attached to a military proving ground on the Chesapeake Bay. The arsenal’s records are boxed and dusting over in the National Archives. Military doctors who helped conduct the experiments have long since moved on, or passed away, and the soldiers who served as their test subjects—in all, nearly five thousand of them—are scattered throughout the country, if they are still alive. Within the Army, and in the world of medical research, the secret clinical trials are a faint memory. But for some of the surviving test subjects, and for the doctors who tested them, what happened at Edgewood remains deeply unresolved. Were the human experiments there a Dachau-like horror, or were they sound and necessary science? As veterans of the tests have come forward, their unanswered questions have slowly gathered into a kind of historical undertow, and Ketchum, more than anyone else, has been caught in its pull. In 2006, he self-published a memoir, “Chemical Warfare: Secrets Almost Forgotten,” which defended the research. Next year, a class-action lawsuit brought against the federal government by former test subjects will go to trial, and Ketchum is expected to be the star witness.

The lawsuit’s argument is in line with broader criticisms of Edgewood: that, whether out of military urgency or scientific dabbling, the Army recklessly endangered the lives of its soldiers—naïve men, mostly, who were deceived or pressured into submitting to the risky experiments. The drugs under review ranged from tear gas and LSD to highly lethal nerve agents, like VX, a substance developed at Edgewood and, later, sought by Saddam Hussein. Ketchum’s specialty was a family of molecules that block a key neurotransmitter, causing delirium. The drugs were known mainly by Army codes, with their true formulas classified. The soldiers were never told what they were given, or what the specific effects might be, and the Army made no effort to track how they did afterward. Edgewood’s most extreme critics raise the spectre of mass injury—a hidden American tragedy.

Ketchum, an unreconstructed advocate of chemical warfare, believes that people who fear gaseous weapons more than guns and mortars are irrational. He cites approvingly the Russian government’s decision, in 2002, to flood a theatre in Moscow with a potent incapacitating drug when Chechen guerrillas seized the building and took eight hundred theatregoers hostage. The gas debilitated the hostage takers, allowing special forces to sweep in and kill them. But many innocent people died, too. “It’s been looked at by some skeptics as a kind of tragedy,” Ketchum has said. “They say, ‘Look, a hundred and thirty people died.’ Well, I think that a hundred and thirty is better than eight hundred, and it’s also better, as a secondary consideration, not to have to blow up a beautiful theatre.”

Not long ago, while debating critics of Edgewood on a talk-radio show, Ketchum argued that the tests were a sensible response to the threats of the Cold War: “We were in a very tense confrontation with the Soviet Union, and there was information that was sometimes accurate, sometimes inaccurate, that they were procuring large amounts of LSD, possibly for use in a military situation.” The experiments, he has said, were no more problematic in their conduct than civilian drug testing at the time.

But Ketchum is an unpredictable apologist. His default temperament is that of an unbiased scientist, trying to solve a stubborn anomaly that just happens to be his life’s work. He accepts criticism of Edgewood thoughtfully and admits the possibility that he is seeing the experiments through a prism of benign forgetfulness. At the same time, as Edgewood’s sole public defender, he must relive history under an unforgiving spotlight. Ketchum often hears from aging test subjects looking for information about what the Army did to them. “I need to know everything that happened to me because it could give me some peace and fewer nightmares,” one veteran wrote to him. In such cases, Ketchum responds with a mixture of defensiveness and empathy. “Well, Mike,” he wrote to another veteran, “I guess some people find it satisfying to look back and condemn what doctors and others did half a century ago, especially if it lends itself to sensationalized movies, and entitles them to disability pensions.” Many of his Edgewood colleagues are far less sanguine about what they did; one told me, “I want to see something happen so this doesn’t happen again.” But Ketchum often wins over skeptics. After many e-mails, Mike told him, “I am certain you did the work for the same reason most of us volunteered. It needed to be done.”

Now retired in northern California, Ketchum has built friendships with psychedelic pioneers, who must also wrestle with the legacy of their work: the bad trips, the personalities misshapen by drugs. In 2007, Ketchum went to Burning Man with his friend Alexander Shulgin, known for promoting the drug Ecstasy. Before they met, Shulgin thought that Ketchum’s research methods were immoral. “To bring a human subject into a psychological storm of this type without preparing him for what might happen, and at the end of his experience to release him to his own devices without having counselled him of the strengths and weaknesses of what did happen, shows a complete disregard of the value of that person,” he had said. But Ketchum evidently convinced him that he was not beyond redemption; in a foreword to Ketchum’s memoir, Shulgin wrote, “It is a pleasure to be able to contribute to this story.”

“I was working on a noble cause,” James Ketchum said of his chemical–weapons tests. Still from untitled test video / Courtesy James Ketchum

Earlier this year, I visited Ketchum in Santa Rosa, where he lives with his fifth wife, Judy Ann Ketchum, in a modest, one-story house in a quiet suburban enclave. Ketchum answered the door in a beige tracksuit. He has the trim stature of an aging athlete, and is tall enough to fill a doorframe, but he is not imposing—his temperament is too readily open, his blue eyes too gently inquisitive. Judy, a retired nurse, is a photographer and artist. In the living room, one of her projects, a platinum-blond mannequin dressed in sequins, stands next to an upright piano, which Ketchum plays. Large closeups of flowers that she has photographed are in every room. The Ketchums are a political hybrid: right-leaning but bohemian, religious but not dogmatic, conservative but open to drug use.

We retreated to a small office to talk. In person, Ketchum projects the image of a man so lost in abstraction that he is easily taken in. As we sat down, he said, “I give money to people who never give it back.” He once gave twenty thousand dollars to a German teacher who said that he was starting a charity; the man took the money and vanished: “He used it to go visit a woman, got drunk with her for four days. I never got it back.” Another swindler took his money for good works in Argentina, which never materialized. “I don’t think about that stuff,” Ketchum told me.

Rows and rows of binders belonging to his archive towered beside us. The trove—including hundreds of pages of sensitive government documents—was an armamentarium of sorts, which Ketchum had been using to inoculate the arsenal’s achievements against obscurity or ill repute, or perhaps just to stir up a little trouble. Lawyers had been arguing over the papers; the C.I.A. had been pressuring him to turn them over. He glanced at the volumes. “They contain a lot of data, with names, doses, graphs of what we did,” he said. “That is definitely something the government would not want to spread around.” When Ketchum left the arsenal, the archive left with him. “It could have been shredded,” he told me. “It could have been locked away.”

The collection seemed to be a living thing, metamorphosing over time as he organized it and re-organized it. I picked up a binder and found a description of the records as he began to save them: “The accumulating volumes stood in rows at first, and then merited their own file cabinet, and eventually, years later, exceeded the capacity of two four-drawer, legal-width, fireproof safes, the unsorted backlog being packed in boxes in the attic, the garage, and a rented storage room.” At times, Ketchum regarded the trove as a vehicle for self-study, but in pessimistic moments he has thought of Jacob Marley—Dickens’s ghost, consigned to purgatory because he had hurt people and lacked the requisite regret to make amends—and wondered if his archive “would eventually become like Marley’s chains, dragging and clanking behind him in a hideous snakelike procession.”

When the lawsuit was filed, in federal court four years ago, a lawyer from the San Francisco firm Morrison & Foerster came calling. He asked Ketchum if he had saved many primary sources. Ketchum turned over the entire trove. “Be open with someone and he’ll reward you,” he told me. Later, during a fifteen-hour deposition, Ketchum answered questions freely, often over his attorney’s objections. He seemed ready to testify—ready for the authority and attention bestowed upon a star witness, ready to put to rest questions about the experiments.

Before I left, Ketchum promised to send me a full digital copy of his archive. A week or so later, a binder arrived at my office, decorated with a photograph of the two of us, which Judy had taken. Inside, Ketchum had constructed a meticulous index to the papers, and for months afterward the raw material came in waves. There were technical reports and scientific tables, lists of soldier volunteers and their test data. There were memos and letters. There were personal items, too: golf scorecards, family photographs, college essays, data on the sale of a house. “I made a list of all the jobs I had in my green notebook, which is the kind of thing I carried around,” Ketchum had told me. “I also made a list of all the drugs I’ve taken.” Tens of thousands of pages of scanned material began to fill up my hard drive. “This is me,” he seemed to be saying. “This is what I did. You be the judge.”

II

“This shall be the story of the fall of a human soul—a fall which is great,” Ketchum wrote when he was a freshman at Dartmouth, working on a play. “Daily, souls are broken. Great men—not great in accomplishment, but great potentially—are rendered forever impotent. This is the tragedy of lost aspiration, defeat, despair.” Ketchum envisioned his protagonist as a young man much like him: a bright student, full of potential, but lost in an institution that was against him, and suffering from a tragic flaw. “The fact is,” he wrote, “he is too ardent, too intense, too uncompromising in his ambitions.”

When Ketchum was eight, his ambition was “to become a scientist and help struggling humanity.” Born in Manhattan during the Depression, and brought up in Brooklyn and in Forest Hills, he was academically inclined, competitive, enthralled with tennis. His mother was a secretary, and his father, who went to college at the age of sixteen and was fluent in many languages, managed two hundred operators for the New York Telephone Company. “He was very religious,” Ketchum says. “Not in a harsh, demanding way but in a reverential sense.” Ketchum’s father was the right-hand man of Norman Vincent Peale, the pastor of Manhattan’s Marble Collegiate Church and the author of “The Power of Positive Thinking.” Peale believed that suffering was largely a thing of the mind, and that faith and “right thinking” could eliminate it. “Truth always produces right procedures and therefore right results,” he wrote.

At Dartmouth, Ketchum was easily distracted. He settled on a double major, psychology and philosophy, but he was not a natural philosopher. “It is a mistake to ask unanswerable questions,” he wrote in one assignment. He became obsessed with his high-school sweetheart, an aspiring actress in New York, and impulsively persuaded her to marry him and run off to Africa or Latin America. They made it only as far as Florida before they returned to Dartmouth—where they found that the marriage voided Ketchum’s scholarship, and had to move into a repurposed barracks near campus. The following year, Ketchum changed paths again: he transferred to Columbia University and, later, enrolled in Cornell University Medical College, to study psychiatry. In New York, he and his wife, living in a rented room with no heat, decided to split up. Ketchum began taking ten milligrams of Dexedrine, first intermittently, then three times a day—a habit that he maintained for decades—and he studied in bouts, memorizing swaths of information. Still, he says, “I couldn’t get awards. They wouldn’t give me cum laude, even.”

Perennially broke, Ketchum decided to join the Army. “It was too much to resist,” he wrote in his memoir. “No longer would breakfast consist of an old pickle jar half-filled with black coffee.” In 1958, having graduated from Cornell, he took a job at the Walter Reed Army Institute of Research. He often woke up at four-thirty in the morning to study cybernetics, and once filled half a room with a gravity-operated “computer” built from soda straws and Tinker Toys. “It produced nothing,” he later wrote, “yet it illuminated that which could not be seen—a logical process.” When the computer did not impress his mentor, he launched another project. During a Thanksgiving holiday, when Walter Reed’s laboratories were empty, he opened up a cat’s brain and embedded electrodes in it, to see if he could give the animal a new way to communicate. He left to play tennis, thinking that a veterinarian would care for the animal, and returned, a week later, to find the cat half-dead from an infection. He tried to nurse it to health in his bathtub, but it had sustained permanent brain damage.