John J. Wilpers Jr., a key member of the Army intelligence unit that arrested Japanese wartime prime minister Hideki Tojo, died Feb. 28. Mr. Wilpers is shown here standing over Tojo in 1945. (Courtesy of the family)

John J. Wilpers Jr., a key member of the Army intelligence unit that arrested and thwarted the suicide of Hideki Tojo, the Japanese prime minister later executed for his war crimes during World War II, died Feb. 28 at a senior living home in Silver Spring. He was 93.

He had complications from dementia, said his son Michael W. Wilpers.

Mr. Wilpers rarely spoke about the dramatic events of September 1945, in the days after the Japanese surrender, when he helped carry out Gen. Douglas MacArthur’s order to locate and take into custody the vanquished prime minister.

Mr. Wilpers’s actions first came to broad public awareness in 2010, when he received the Bronze Star Medal for his role in the arrest. His commanding officer recommended the decoration in 1947, but the paperwork apparently disappeared and remained lost until Mr. Wilpers made an inquiry nearly six decades later.

He made the query because he “felt the gray hand of old age sneaking up” on him, he told The Washington Post after receiving the medal, and not because he wished to glorify his actions or the realities of war.

John J. Wilpers Jr., left, with his son John J Wilpers III and daughter Helen Wilpers Read, who are holding a photograph of their father standing over the wounded World War II Japanese leader Hideki Tojo that appeared in publications worldwide. (Office of Congressman Chris Van Hollen/Via AP)

“All of this was very sad,” he said. “I didn’t want to do anything to describe it as wonderful. What happened happened. Like any war, it should be regretted.”

At the time of the Japanese surrender, Mr. Wilpers was a 26-year-old lieutenant serving with an intelligence unit in Tokyo. Tojo had directed his country’s surprise attack on Pearl Harbor on Dec. 7, 1941, and ranked high on the list of Japanese leaders wanted on war crimes charges.

Aware of this, Tojo had gone into seclusion and, as Mr. Wilpers would soon discover, he was preparing to commit a sort of ritual suicide.

Mr. Wilpers credited U.S. journalists with helping to locate Tojo at his home in suburban Tokyo. When he and his unit converged on the property, an interpreter informed Tojo that MacArthur’s representatives had come to call on him. Tojo poked his head out the window before retreating back inside.

Mr. Wilpers heard a gunshot.

He forced his way into the building and “kicked his big GI shoes” through a second door, according to an account in Yank magazine. He found Tojo “slumped in a chair with a smoking pistol grasped in his hand and blood gushing from a wound in the left side of his chest.”

“I was trying to keep one eye on him and one on the pistol,” Mr. Wilpers told the Associated Press years later.

Mr. Wilpers had a simple order: to find Tojo and bring him back alive. According to the 1947 account by his commanding officer, Mr. Wilpers found a Japanese physician to administer emergency aid. The doctor initially resisted but complied after Mr. Wilpers confronted him with a revolver.

Tojo was eventually removed to a military hospital and, in 1948, tried and executed as a war criminal.

Through Mr. Wilpers’s “initiative, ingenuity and courage,” reads his Bronze Star Medal citation, “the United States Army captured and detained Hideki Tojo.”

Mr. Wilpers stopped Tojo from “taking his own life,” the citation continues, “thereby assuring that he would live and stand trial for his ignominious war crimes.”

John Joseph Wilpers Jr. was born Nov. 11, 1919, in Albany, N.Y. His father worked in a speakeasy and a pool hall and, among other professions, was a bookie.

The younger Mr. Wilpers graduated from the University of Toronto in 1942 and then joined the Army Air Forces. He later shifted to the intelligence unit and, after the war, joined the new CIA. He spent his career at the spy agency, with assignments including the supervision of a staff that profiled Soviet and Chinese scientists. He retired from the CIA in 1975 and from the Army Reserve in 1979 as a colonel.

His wife of 57 years, Marian Meyer Wilpers, died in 2006. Survivors include five children, John J. Wilpers III of Marshfield, Mass., Mary Amory of Camden, Maine, Teresa K. Wilpers of Baltimore, Michael W. Wilpers of Takoma Park and Helen Wilpers Read of Seattle; and seven grandchildren.

Mr. Wilpers was reported to be the last surviving member of the unit that arrested Tojo. Until the end of his life, he expressed modesty about his role in history.

He told the Associated Press in 2010, “I just happened to be the one who busted open the door.”