The Vatican today said there were "signals" starting in 2013, some of them provided anonymously, about the case at St. Pius X Pre-Seminary, which serves middle- and high school students.
It said officials at the seminary and the bishop of Como investigated, but didn't find "adequate" confirmation.
Italian journalists recently reported that the older student was 14 years old when he started demanding sex at night from a 13-year-old.
Students at St. Pius X serve as altar boys for papal Masses in St. Peter's Basilica.