On the eve of a board of trustees meeting called to consider changes to the Greek system at Pennsylvania State University, the parents of fraternity pledge Tim Piazza have called for the expulsion of the students and the firing of the employees they say are responsible for their son's death.

"It is time for Penn State to take the lead," James and Evelyn Piazza wrote in a four-page letter to the board. "The whole country is watching."

The Piazzas urged the board to set guidelines that would call for all students found guilty of hazing or failing to report it or furnishing alcohol to minors at Greek socials to be subject to expulsion. They also asked university officials to stand with them in fighting for tougher laws against hazing, and demanded that the university accept responsibility for their son's death.

"Our son died on your watch because of ignorance and denial by Penn State," the Lebanon, N.J., couple, both accountants, wrote. "It's time to admit responsibility so that the university can move forward."

In response to the letter, Penn State issued a statement that read, "Our focus is on solutions to the problems of student alcohol misuse, hazing and other misconduct.  Tomorrow (Friday), at 1 p.m. during the public session, the university will discuss our plans to advance student safety. "

Piazza, a 19-year-old sophomore engineering major, was forced to drink large amounts of alcohol and later fell down some stairs during a Beta Theta Pi pledge night party in February, according to the grand jury presentment that indicted 18 fraternity members in his death on charges ranging from involuntary manslaughter to aggravated assault and hazing. No one called for emergency help until about 12 hours after he was injured during the fall down the stairs.

In the interim, Piazza was slapped, had liquid poured on him, and fell several other times. Piazza died of a non-recoverable brain injury, a ruptured spleen, and a collapsed lung.

"I realize some of the students are children of alumni and prominent business figures in PA," Jim Piazza wrote of students he holds responsible for his son's death, "but they committed serious crimes … What are you waiting for? It's time to act."

He called on the university to fire Damon Sims, vice president for student affairs, who led a 2015 task force on Greek life, and Tim Bream, the head football trainer and assistant athletic director at Penn State, who also served as the live-in adviser to Beta Theta Pi. Bream, 56, was home the night of the party though not present for it, authorities have said. The grand jury did not charge Bream, but the Piazzas hold him responsible nevertheless.

"He turned a blind eye for years," the couple charged.

The Piazzas also blamed Penn State.

"Yes, he died at the hands of men who had no regard for human life, but that behavior was fostered and accepted at Penn State for a long time," they wrote of their son.

Penn State's board has permanently banned the fraternity. It also instituted a moratorium on alcohol at social events last semester, reduced the number and size of allowable parties, and banned kegs and hard liquor.

Last month, university officials said they plan more changes, including publishing "report cards" on fraternities and sororities with their conduct history. The board is meeting in private Friday morning to discuss potential changes and university officials plan to make an announcement in the afternoon.

The Piazzas also called on the university to mandate that their spot checkers be allowed to go anywhere in a fraternity house to ensure that rules are being followed, not just the public areas.

The couple emphasized that they are not trying to kill Greek life at Penn State, but they want to make it safer.

"Greek life at Penn State is broken and must be fixed," they wrote.