Columbia football coach Pete Mangurian has resigned after a winless season and after reports of a letter that accused him of abusive coaching tactics.

Mangurian's resignation Friday came a day after the Columbia student newspaper reported that a letter from players was given to the university accusing the coach of verbal and physical abuse and trying to force players to play with concussions.

The letter was later retracted. But the university acknowledged the letter and that it investigated whether injured players were mishandled and "found no evidence to support an allegation of a departure from that protocol with our football players."

Mangurian was 3-27 in three seasons at the Ivy League school, and the university had hired a consultant to review the program.