Former students of a prestigious Rhode Island boarding school are calling for an independent investigation into sexual abuse that they say spanned three decades and involved at least seven former staff members.

St. George's School in Middletown announced last month that it found 26 students were sexually abused by six school employees in the 1970s and 1980s. It acknowledged it didn't report abusers to authorities.

During a news conference Tuesday in Boston, three former students called for an independent investigation and called on the school to set up a victims' assistance fund for mental health counseling.

The school's current headmaster didn't immediately return a call seeking comment.

Rhode Island State Police began investigating in November.

About 400 students attend the private high school, with annual tuition of $56,000.