"Our decisions were guided by our obligation as trustees, always, to put the interests of the university first," said the statement posted on the university's web site.
The trustees voted to remove Spanier, the statement said, because he "took insufficient action after learning of a 2002 incident" involving Sandusky. In that incident, former assistant football coach Mike McQueary, then a graduate assistant, reported that he had seen Sandusky having sex with a young boy in a campus shower. Spanier had said it was reported to him as "horsing around."
"This failure of leadership included insufficiently informing the board about his knowledge of the 2002 incident," the statement said.
Spanier early on also defended the actions of athletic director Tim Curley and vice president Gary Schultz without board authorization. Both had been charged with perjury by the Grand Jury investigating the Sandusky case.
The trustees ousted Paterno with only three games remaining in the 2011 season because he didn't do enough upon learning of the 2002 incident, the statement said.
They cited the grand jury report that quoted Paterno on what McQueary had told him - that McQueary had seen Sandusky "in the Lasch Building showers fondling or doing something of a sexual nature to a young boy."
"While Coach Paterno did his legal duty by reporting that information the next day, Sunday, March 3, to his immediate superior, the then Penn State Athletic Director Tim Curley, the Board reasonably inferred that he did not call police," the statement said. "We determined that his decision to do his minimum legal duty and not to do more to follow up constituted a failure of leadership by Coach Paterno."
The board said it has intended to name Paterno head coach emeritus and take other steps to honor him, but will hold off on taking that step until the conclusion of the university internal investigation of the scandal.
Contact Susan Snyder at 215-854-4693 or firstname.lastname@example.org or on Twitter @ssnyderinq