Brian Seed, a professor of genetics at Harvard Medical School, said he sat next to Wiley during the board meetings on Nov. 15.

“He didn’t seem particularly different [than usual], but it’s hard to gauge people’s emotional distress,” Seed said. “A lot of times people are good at concealing things.”

Larry J. Shapiro, a professor of pediatrics at the University of California at San Francisco Medical School and a member of the scientific advisory board, said Wiley had given no indication that he would not attend the meeting’s closing session on the morning of Nov. 16.

A disappearance of a Harvard professor last occurred in 1987, when Lawrence Kohlberg, professor at the Graduate School of Education, was missing for nearly three months before investigators found his body in Boston Harbor.

His abandoned car was found four days after he was reported missing.

Although police are searching for clues to the Wiley case in Memphis, a post-doctoral fellow who works with Wiley said that authorities have not searched his Cambridge lab.

The Wiley story has received growing national and international attention, from The Daily Telegraph in Sydney, Australia to The New York Times.