Jerome Karle is shown here with his wife, Isabella. (The Washington Post file photo)

Jerome Karle, a U.S. Naval Research Laboratory scientist who shared the Nobel Prize in chemistry for discovering a way to determine the structure of molecules, a breakthrough that made possible significant advances in medicine and other fields of science, died June 6 at the Leewood Healthcare Center in Annandale. He was 94.

The cause was liver cancer, said his daughter Louise Karle Hanson.

Dr. Karle was a scientific polymath, schooled in biology and chemistry but proficient as well in physics and mathematics. He shared the 1985 Nobel Prize in chemistry with the late Herbert A. Hauptman, a mathematician with whom he pursued his pioneering research in the 1950s and ’60s at the Naval Research Laboratory in Southwest Washington.

The two men and their colleagues — including Dr. Karle’s wife, Isabella Karle, a chemist at the lab — took on a problem that had vexed scientists for years: the challenge of discerning the structure of three-dimensional molecules, combinations of atoms that were the simplest units of chemical compounds. They were too small for the most powerful of optical microscopes.

In the early part of the 20th century, the development of a technique called X-ray crystallography had made it possible to determine the probable shape of molecules. The technique involved buffeting a crystallized form of the molecule with X-rays and studying the patterns made on photographic film by the reflected beam, an effect compared to the reflection of light off a mirrored disco ball.

But it was a laborious process that could take months or years to complete. Dr. Karle and his colleagues devised an alternate, mathematical process relying on measurements including the intensity of the reflected X-rays. It allowed scientists to determine molecular structure more directly, precisely and quickly.

First published in the early 1950s, the discovery was overlooked for years. Dr. Karle credited his wife with drawing attention to the method’s usefulness. (“I do the physical applications, he works with the theoretical,” she told The Washington Post. “It makes a good team. Science requires both types.”)

The applications were numerous and transcended fields of science. Dr. Karle’s work has been applied to research on the structure of DNA, the development of painkillers and drugs to treat breast and other types of cancer, the study of hormones and antibiotics, and military research on propellants for missiles.

“It is almost impossible to give an example in the field of chemistry where this method is not being used,” a Nobel judge was quoted as saying when the prize was announced. The citation honored Dr. Karle and Hauptman for making “outstanding achievements in the development of direct methods for the determination of crystal structures.”

Dr. Karle had worked for the Naval Research Laboratory for more than six decades when he retired in 2009 as chief scientist in the laboratory for the structure of matter. He was once asked why he had never joined the private sector, where his earning potential would have been much greater.

“I’m not quite sure young people understand this,” he said, “but it’s quite possible to do good research for the Navy and the Department of Defense and at the same time do good science.”

Jerome Karfunkle was born June 18, 1918, in Brooklyn, the son of immigrants from Eastern Europe. He later changed his surname to Karle. His father was a Coney Island businessman; his mother, a homemaker, was a pianist and organist.

He received a bachelor’s degree in biology from City College of New York in 1937. Hauptman was in his class, although they did not know each other at the time. Another classmate was Arthur Kornberg, a biochemist who shared the 1959 Nobel Prize in medicine for his work on DNA.

Dr. Karle went on to receive a master’s degree in biology from Harvard University in 1938 and a doctorate in physical chemistry from the University of Michigan in 1943, his daughter said.

He met his future wife on the first day of a physical chemistry lab at Michigan. Places in the lab were assigned alphabetically by last name. And so it turned out that Karle, Jerome was next to Lugoski, Isabella.

They were married in 1942 and settled in the Washington area shortly thereafter to join the Naval laboratory.

Survivors include his wife, of Lake Barcroft; three daughters, Louise Karle Hanson, a chemist, of Long Island, Jean Karle, also a chemist, of Vienna and Madeleine Karle Tawney, a geologist, of Lake Barcroft; and four grandchildren.

During World War II, Dr. Karle worked in Chicago on the Manhattan Project, which resulted in the development of the atomic bomb. In Washington, he taught physics and mathematics at the University of Maryland while pursuing his laboratory research. He was elected to the National Academy of Sciences in 1976; his wife followed two years later.

The awarding of the Nobel came as something of a surprise. Dr. Karle was 39,000 feet over the ocean on a transatlantic flight when the pilot made an announcement over the loudspeaker.

“We are honored to have flying with us today America’s newest Nobel Prize winner, and he doesn’t even know it,” the captain said from the cockpit, according to a news account.

“In fact, the award is so new that Dr. Jerome Karle, located in seat 29C, left Munich this morning before he could be notified that he was a recipient of the Nobel Prize in chemistry.”

In the cabin, he was feted with champagne.