Among those who questioned Walker: the chair of his high school science department, Ann Serpe, 73. “Answer the question when they ask you!” Serpe said in an interview. “He could have manned up a bit. That’s what I would tell him.”

Serpe, who taught chemistry and chaired the math and science department at Delavan-Darien High School in Delavan, Wis., before her retirement in 1998, now lives in nearby Elkhorn. She recalls that Walker, her pupil and an advisee in student government, was a bright, committed participant in class. Walker graduated in 1986.

What would Walker have learned in high school? “We taught the theory of evolution, and human evolution, as a prerequisite to understanding biological classification. I went out and looked at my biology textbook just to make sure.”