"It seemed like a thing out of a Bond movie," he recalled years later. "We were all dressed in our Adam hats and cover cloth coats. . . . Ten or 12 agents would drop off: Syracuse, Buffalo, Chicago. The train kept going west."
Safferstein's group disembarked in New Mexico. Two cars took them to a wooded area where they met Maj. Peer DeSilva, the laboratory's commander.
"He explained to us for the first time this ultra top-secret mission, that they were working on a bomb that would be able to dig a hole into the ground some 80 to a hundred feet deep and perhaps 5, 10 miles long. And that from this point on, you are in the Manhattan Project," Safferstein recalled.
Duty later called Safferstein to the Mariana Islands in the western Pacific, where U.S. forces had built airfields to launch long-range raids on Japan itself, and in mid-1945 the two bombs from Los Alamos had been secretly delivered by Navy ship.
About 12 hours before "Little Boy" was placed aboard the aircraft Enola Gay, a scientist appeared at a Quonset hut on the island of Tinian to make final adjustments.
He "explained the whole function of this bomb," Safferstein recalled. "And then he left and here I am alone with 'Little Boy.' And so I walked over to it, saw that there were some initials on it . . . and added my signature to the bomb."
Though "extremely proud" to be part of history, Safferstein was not impervious to the ravages of war.
After the bombs were dropped, Safferstein accompanied a team that included U.S. doctors who surveyed the damage in Japan. Deeply moved by its "beautiful people," he recalled thinking: "Let's . . . never have to use it again."
He said that after the war, Groves urged him to remain in counterintelligence, but he decided on civilian life. He returned to supermarkets, became president of Storecast Corp., a merchandising and marketing company, and then started Long Island-based Supercast and its spinoff, In-Store Distributing.
In addition to Bernice and Michael Safferstein, survivors include another son, Dr. Don Safferstein; a daughter, Barbara Abramsky; and five granddaughters.