The former Archbishop of Boston, Cardinal Bernard Law, has begun testifying before a grand jury investigating whether charges should be filed against him or other Church members for their handling of sexual abuse cases.
Cardinal Law arrived on Monday morning at the office of Massachusetts State Attorney General Thomas Reilly, where the grand jury is meeting.
He is the first US cardinal known to have been subpoenaed by a grand jury since the Boston diocese was rocked in January 2002 by allegations of sexual misconduct by dozens of priests over a time span of decades.
Eight other church officials have been ordered to testify before the jury regarding their handling of alleged abuse cases, the Associated Press news agency reported.
Cardinal Law resigned from his position as Boston archbishop in December following allegations he had moved paedophile priests from one pulpit to another rather than confront accusations that they had sexually assaulted children.
He has since spent his time at a private retreat at a Benedictine monastery near Pittsburgh in the US state of Pennsylvania.
Documents released by the Church contain accusations that a priest molested a 17-year-old on 21 consecutive nights as they drove across the country.
Others allege that Cardinal Law recommended one of his priests for a job as military chaplain saying there was no reason he should not work with young people after the church paid $200,000 to the family of a youth allegedly abused by the priest.
There were also claims that priests had fathered children, traded cocaine for sex with boys, and abused girls training to become nuns.
The Boston diocese now faces some 450 lawsuits alleging child abuse and is considering filing for bankruptcy.
It has also triggered a financial crisis over compensation to abuse victims which could amount to tens of millions of dollars.
Following the scandal the Vatican approved a revised plan to combat child sex abuse in the scandal-tainted US Roman Catholic Church.