Dr. Richard Axel, a Nobel Prize-winning scientist, said he is stepping down as co-director of Columbia University’s Zuckerman Mind Brain Behavior Institute on the heels of his association with notorious sex predator Jeffrey Epstein drawing public attention.

“My past association with Jeffrey Epstein was a serious error in judgment, which I deeply regret,” Axel said.

Axel won the Nobel Prize in Physiology or Medicine in 2004 with Linda Buck “for their discoveries of odorant receptors and the organization of the olfactory system,” the prize website notes.