“The buck always stops with me,” Oprah Winfrey told South African reporters Monday morning, just hours after Johannesburg police released on bail a dormitory matron accused of assaulting pupils at her school.

Though she does not personally do any hiring at the Oprah Winfrey Leadership Academy for Girls, the U.S. talk show host said the screening process has been inadequate and said some school officials had hidden facts of the case from her.