It was planned as a solemn event -- a chance to experience the sacred liturgical roots of Catholic tradition at one of the country's most prominent churches. But after three years of fundraising and careful coordination, an elaborate Latin Mass scheduled for Saturday at the Basilica of the National Shrine of the Immaculate Conception in Washington has been dragged into the clergy abuse scandal.

Advocates for abuse victims voiced outrage Tuesday that the former Vatican official invited to lead the Mass -- Cardinal Darío Castrillón Hoyos of Colombia -- once praised a French bishop for not telling police about a priest who had sexually assaulted children. Survivors Network of those Abused by Priests sent letters Tuesday to Pope Benedict XVI and Washington Archbishop Donald W. Wuerl, calling on them to condemn Castrillón's remarks and replace him in the Mass.

"To hold the cardinal up in a position of honor and leadership after what he's said would just rub salt in to the wounds of millions of betrayed Catholics and thousands of wounded victims," said David Clohessy, SNAP's director.

At the center of the debate is Castrillón, the former head of the Vatican's Congregation for the Clergy, who made headlines last week when a 2001 letter he wrote to French Bishop Pierre Pican surfaced in the French press. In it, he praised Pican for not reporting the pedophile priest to police, despite being mandated to do so under French law.

"I congratulate you for not denouncing a priest to the civil administration," Castrillón wrote, after Pican was convicted of failing to report sex crimes against children. "You have acted well, and I am pleased to have a colleague in the episcopate who, in the eyes of history and of all other bishops in the world, preferred prison to denouncing his son and priest."

At the time the letter was written, the priest, the Rev. René Bissey, had been sentenced to 18 years in prison for repeatedly raping a boy and for sexually assaulting 10 other children.

On Saturday, Castrillón ignited another firestorm when he claimed that Benedict's predecessor, Pope John Paul II, not only approved of his letter but also instructed him to send copies to bishops worldwide.

As the controversy unfolded, organizers of the Washington Mass watched in dread. Furious protests were the last thing the Paulus Institute expected when it invited Castrillón more than a year ago to lead its first major event.

"All we wanted to do is promote sacred liturgy," said Paul King, president of the Paulus Institute, which was formed in 2007 to preserve older forms of worship. "The reason we invited him is it's a complicated Mass. There aren't a whole lot of bishops who can say it and are available."

At first, King said, divine providence seemed to shine on their efforts. Scheduling conflicts at the Basilica -- the largest Catholic church in North America -- had made it impossible to hold the event in 2008 and 2009. So it was with care that organizers picked April 24, 2010, for their Mass. Weeks later, they realized it coincided with the