The Wall Street Journal reports that Poly Prep officials sent an email to students and alumni on Friday offering "deepest apologies" to those who were abused by the coach, Philip Foglietta.
Foglietta was accused of groping and raping boys during his tenure at Poly Prep from 1966 to 1991. He died in 1998.
The school settled a lawsuit over the abuse in 2012.
Poly Prep eventually forced Foglietta's retirement, but school officials did not publicly acknowledge the reasons behind his departure.
The letter from headmaster David B. Harman and board Chairman Scott M. Smith says the school should have immediately reported Foglietta to the authorities.