As a child in Austria, Walter Littman escaped the Nazis in an extraordinary tale of survival, mettle and luck.

Littman, of Minneapolis, later became a noted mathematician at the University of Minnesota for a half-century, beloved by family, friends, colleagues and students. He died of COVID-19 in April. He was 90.

He was born in Vienna on Oct. 17, 1929. His life — and the lives of thousands of other Jews — tragically changed when the Nazis annexed Austria in March 1938. His father, Leon, a fabric merchant, was arrested in the Kristallnacht pogrom that destroyed synagogues and Jewish-owned businesses the following November.

His father escaped almost-certain execution because he coughed while being interrogated by the Nazis, according to the family. Believing Littman was days away from death, S.S. Capt. Adolf Eichmann, one of the architects of the Holocaust, reportedly told him he “wasn’t worth the bullet,” the family said.

Leon Littman was released, but the family had just days to flee Austria, or face deportation to a concentration camp.

The Littmans escaped to Sweden where they stayed for two years while awaiting U.S. visas. The family ultimately settled in the Lower East Side of New York City, opening a drapery business. Walter was accepted to the prestigious Stuyvesant High School, known for its programs in science, technology and mathematics. There, his love of math flourished.

Littman received undergraduate and doctorate degrees in mathematics from New York University. After a stint at the University of California, Berkeley, he landed at the U in 1960, later retiring from teaching in 2010.

“He was a very positive person, he had a good sense of humor. I’ve never seen him angry,” said his friend and colleague, Avner Friedman, a distinguished professor of mathematics at Ohio State University.

The stereotypical absent-minded professor, Littman’s office “was a big mess. If you wanted to sit down, you’d have to pick up three books,” Friedman laughed. “But he knew exactly where everything was.”

In addition to his beloved equations, Littman enjoyed classical music, particularly the work of Austrian composer Franz Schubert, said his son, Benjamin, of California.

“He was such a kind person, it was so enjoyable to spend time with him,” his son said.

Littman is also survived by his wife, Florence of Minnesota; daughter Miriam Cisternas of Washington; son Philip of Israel; and five grandchildren.