Jack Steinberger, a German-born physicist who came to the United States as a boy to escape the Nazis and went on to win the Nobel Prize for his work with neutrinos, one of the most elusive and mysterious of all the elementary constituents of matter, died Dec. 12 in Geneva. He was 99.

Family members confirmed his death but did not provide an immediate cause.

An American citizen whose prizewinning work had been conducted at Columbia University in New York and the Brookhaven National Laboratory on Long Island, Dr. Steinberger had spent the latter part of his life at the CERN nuclear research center in Switzerland.

Over a long and productive life, Dr. Steinberger experienced and embodied some of the main currents of the history of his times. The rise of the Nazis sent him to America before World War II. But as part of the postwar effort of his native Germany at reconciliation, he saw the school he had attended there named in his honor.

After being rescued from Europe through human generosity and taken in by an American foster family, he demonstrated generosity in his turn, donating his Nobel medal to the public high school he attended as a refugee in a suburb of Chicago.

In his professional life, he rose from a humble background, served in the U.S. Army during the war and reached the highest levels of physics, making an important contribution to the effort to understand the particles and forces that characterize matter and the universe.

He and two others, Leon Lederman and Melvin Schwartz, shared the 1988 Nobel in physics for their technique for producing high-energy beams of neutrinos and for showing the existence of two types of neutrino. Their experiments, conducted in 1962, were regarded as milestones in particle physics.

They were designed as a foray into the incompletely understood world surrounding one of the four fundamental forces of nature. They made what was described as the first experimental study at high energies of interactions involving the “weak force.”

Two of nature’s four basic forces — gravity and electromagnetism — are well known. Less familiar from our observations of the everyday world are two forces vital in nuclear and elementary particle reactions. These are the strong force and the weak force.

The prizewinners studied weak-force interactions at high energies by creating a beam of neutrinos, which do not interact through the strong force but do so by the weak interaction. Dr. Steinberger and his colleagues obtained their high-energy neutrinos by a multistep process that began with high-energy collisions in a particle accelerator.

Protons from a synchrotron were flung against a target of beryllium atoms. That collision produced particles known as pions. The decay of those particles yielded the desired neutrinos. Then it became a matter of separating the neutrinos from the accompanying nuclear debris.

It was the go-through-anything unstoppability of neutrinos that offered a solution to that problem. Armor plating from a scrapped warship was assembled, to a thickness of more than 40 feet. That barrier was impervious to all particles but neutrinos.

Then a detector weighing tons was put in the path of the beam, sufficiently massive to ensure that even the stealthy, ghostlike neutrinos would hit something, provided enough of them were aimed at it.

Ultimately, after operating the experiment for months and beaming an essentially unfathomable number of neutrinos (estimated at 100 million million) at the target, the scientists observed less than 60 of the occurrences they hoped to find.

These produced not the electrons that might have been expected, but muons, 200 times heavier than electrons. It was enough to show the existence of two types of neutrino, one associated with the electron, the other with the muon.

In demonstrating the existence of two forms of the neutrino, the work became known in the world of physics, at least, as “the two neutrino experiment” prompting Lederman to quip that “the two neutrinos” sounded like an Italian dance team.

But the pairings were serious business to the creators of physical theory.

By giving a neutrino of its own to both the electron and the muon, the pairing up helped show how to organize and account for the growing table of elementary particles. These seemed to be emerging in bewildering profusion from experiments at ever-higher energies.

A systematic way of organizing them and the forces that they exerted seemed a pathway to describing the basic structure and behavior of the universe. Physicists called this system of organization the standard model. Dr. Steinberger’s work provided valuable insight into the workings of the model.

Hans Jakob Steinberger was born May 25, 1921, in the Bavarian town of Bad Kissingen. The name of the town became that of one of the ancestors of Henry Kissinger. But the former U.S. secretary of state was born elsewhere in Germany; a German newspaper suggested that Dr. Steinberger may be the most celebrated son of Bad Kissingen.

Dr. Steinberger’s father, a World War I veteran of the German army, was a prayer leader and teacher for the small Jewish community in Bad Kissingen. But with the rise of the Nazis, it became clear that the Steinbergers had little future in Germany.

An American organization volunteered to bring 300 Jewish children to the United States. In 1934, Dr. Steinberger and his older brother were placed aboard a ship, headed for America.

In four years, the rest of the family joined them, and it was arranged for the parents to run a delicatessen.

Dr. Steinberger graduated from New Trier High School in Winnetka, Ill., and received a chemistry degree from the University of Chicago in 1942. During World War II, the Army sent him to the radiation laboratory at the Massachusetts Institute of Technology, where radar was being developed. He earned a doctorate from Chicago in 1948.

He said he spent a year at the University of California at Berkeley and left because, although he was a not a communist, he declined on principle to sign a loyalty oath attesting to that. Instead, he became a member of the faculty at Columbia from 1950 to 1971, rising to the rank of full professor. From 1968 to 1986, including a brief overlap at Columbia, he was a physicist at the European Organization for Nuclear Research (known as CERN) in Geneva.

In 1988, he was a spokesman for a collaboration of about 350 physicists, preparing a detector called ALEPH, for the CERN electron-positron collider then under construction. Its measurements, vital and exact, offered important confirmation to the standard model.

As a manager, Dr. Steinberger said that for some time, he could contribute, not only through administration and guidance, but also through design and analysis of the physics involved.

But by 1995, he said, that came to an end because the challenges of the work became increasingly technical, particularly with the use of computers, and, he added, “I could not compete with the younger generation.” Instead, he turned his attention to cosmology and astrophysics and the physics entailed in these disciplines.

In addition to the Nobel, his honors included the U.S. National Medal of Science.

His first marriage, to Joan Beauregard, ended in divorce. Survivors include his wife, Cynthia Alff; two sons from his first marriage; and two children from his second marriage.

Dr. Steinberger visited his old high school in Illinois in 1997, spending time with students, faulty and the science department. Three years later, according to the school, a package arrived with foreign stamps in the corner.

Inside, wrapped only in paper, was Dr. Steinberger’s gold Nobel medal.

“The good beginning I received at New Trier was one of several important privileges in my life, and it is a pleasure to leave that token in good hands,” he wrote at the time.

Such medals have an intrinsic value estimated at about $10,000. According to news accounts, one was recently sold for more than $700,000.