Princeton University math whiz Michael Lohman had a creepy sexual secret, cops say.

For three years, the married grad student quietly terrorized Asian women on campus by clipping snippets of their hair, spraying them with urine and pouring semen or urine in their drinks at university dining halls, cops say.

When investigators finally caught up with Lohman and arrested him last week, they searched his campus apartment and found women’s hair stuffed into mittens that he apparently used for sexual gratification, said Princeton Borough Police Lt. Dennis McManimon.

Lohman also had lingerie and other clothing believed stolen from women around campus, McManimon said.

Cops say they can link Lohman to 50 incidents involving Asian women.

Police began getting bizarre complaints involving Asian women soon after Lohman, a Ph.D. candidate, arrived at Princeton in the fall of 2002.

Investigators never put the incidents together until a complaint March 11 by a woman who said her hair was cut on a shuttle bus. That woman saw where Lohman got off the shuttle, evidence, McManimon said, that helped identify him as a suspect.