Wilpers died Thursday at an assisted living facility near his home in Garrett Park, Md., his son John J. Wilpers III said Monday.
The upstate native was part of a five-man unit ordered to arrest Tojo at his home in a Tokyo suburb on Sept. 11, 1945, nine days after Japan's surrender ended the war. While the soldiers were outside, Tojo attempted to commit suicide by shooting himself in the chest. Wilpers ordered a Japanese doctor at gunpoint to treat Tojo until an American doctor arrived.
Tojo survived, was convicted of war crimes and was executed in December 1948.
Wilpers, a retired CIA employee, didn't give media interviews until 2010, when he was awarded a belated Bronze Star by the Army.
"He was terribly proud of what he did but was not boastful," his son John told The Associated Press.
Wilpers, a 25-year-old lieutenant from Saratoga Springs, was on the detail Gen. Douglas MacArthur dispatched to arrest Tojo, sought by the Allied powers so he could be tried for atrocities committed by Japanese troops during the war.
After arriving at Tojo's house, the Americans heard a gunshot from inside. Wilpers kicked in a door to find Tojo slumped in a chair, his white shirt covered in blood. The bullet had missed his heart but left Tojo severely wounded.
According to reporters and photographers who followed the unit into the room and Wilper's own account given to the AP three years ago, Tojo's house staff and a Japanese doctor were reluctant to help until Wilpers pointed his gun at the physician and ordered him to start treatment. An American Army doctor and medical staff eventually showed up and kept Tojo from dying.
Wilpers went on to a 33-year career with the Central Intelligence Agency. He and his wife, Marian, who died in 2006, raised five children while living in a Washington, D.C., suburb, but he didn't tell any of them about his wartime experiences until decades later.