Former governor of Oklahoma Mr Frank Keating has resigned as chairman of a panel of lay Catholics examining sex abuse in the US Catholic church.
In his resignation letter, he stood by his recent accusation that some Roman Catholic bishops have shown a Mafia-like devotion to secrecy.
"My remarks, which some bishops found offensive, were deadly accurate. I make no apology," Mr Keating wrote in his letter. "To resist grand jury subpoenas, to suppress the names of offending clerics, to deny, to obfuscate, to explain away; that is the model of a criminal organisation, not my church".
The US bishops' conference established a review board a year ago at a meeting in Dallas in which they promised to remove permanently from ministry any priest who has ever sexually abused a minor.
On the day he was appointed, Mr Keating said that some bishops probably should be prosecuted. Several weeks later, he antagonised the bishops again by suggesting that Catholics in some dioceses should withhold donations to force change.
Mr Keating's tendency to speak plainly had repeatedly irritated Catholic prelates. The most recent was Cardinal Roger Mahony of Los Angeles, who called for Mr Keating's removal after the former FBI agent told the Los Angeles Timeslast week that some bishops were acting like "La Cosa Nostra".
But lay leaders said Mr Keating's outspokenness had also increased public confidence that his 13-member panel, known as the National Review Board, was truly independent and would not whitewash the sex abuse scandal.
AP