One of two young men at the heart of a criminal rape and conspiracy case has sued the Archdiocese of Philadelphia in connection with his alleged sexual abuse as a 10-year-old altar boy in 1999.

Using the pseudonym "Billy Doe," the plaintiff, now 23, says church officials put him in harm's way by assigning a known abuser, the Rev. Edward Avery, to his parish, St. Jerome's in Northeast Philadelphia.

There he was raped and sodomized by Avery, another priest, and a teacher, according to the lawsuit filed Monday in Common Pleas Court.

His lawyers say church officials, including Cardinal Anthony J. Bevilacqua, exhibited "callous indifference to the safety and well-being of children" by ignoring a psychiatrist's recommendation that Avery not be given unsupervised access to children.

Unlike many sex-abuse suits brought against the archdiocese, this one was filed within the statute of limitations for civil claims. As such, it could be the first to proceed to trial.

For years, courts routinely tossed out such suits because the victims came forward too late. Recent changes in Pennsylvania's statute of limitations allow more time.

Through spokeswoman Donna Farrell, archdiocesan officials declined to comment on the suit Monday.

In addition to Bevilacqua, the filing names the Rev. William J. Lynn, former head of the archdiocesan clergy office, and Billy's alleged abusers: Avery, the Rev. Charles Engelhardt, and former parochial-school teacher Bernard G. Shero.

Avery, Englehardt and Shero are facing felony charges in connection with the alleged assaults against Billy, who filed a criminal complaint against them in 2010. They have pleaded not guilty. Lynn, also criminally charged, has denied that he conspired to endanger the welfare of children.

Billy's allegations, and those of another young man who said he was raped by the Rev. James Brennan in 1996, launched a grand jury investigation in 2010 into sex abuse in the archdiocese - the second such panel to be convened in less than six years.

In February, the grand jury not only recommended the criminal charges but accused the archdiocese of harboring dozens of priests accused of misconduct with minors. Many of those priests have been suspended pending an archdiocesan investigation.

The criminal case has also attracted national attention because Lynn, 60, is the first high-ranking member of a Catholic diocese in the United States to be criminally charged with conspiracy to endanger the welfare of a child.

During his 12 years as Bevilacqua's secretary for clergy, Lynn was responsible for recommending priests' parish assignments and for handling complaints of clergy sex abuse.

Both the lawsuit and the child-endangerment charge against Lynn note that in 1992, the archdiocese had a report that Avery had molested a 19-year-old male. After treatment, doctors advised the archdiocese not to assign him to unsupervised ministry with children.

Instead, both cases assert, Lynn recommended Avery for St. Jerome's, knowingly putting Billy and other children at risk.

Billy's lawyers, Slade H. McLaughlin and Paul A. Lauricella, said they do not expect their civil suit to be heard before next year, after the criminal case is settled.

Bevilacqua was archbishop of Philadelphia from 1988 to 2003.

Lynn and the four other defendants are scheduled to appear Friday in Common Pleas Court for a pretrial hearing in the criminal case, which is unrelated to the civil suit.

On Friday, the District Attorney's Office introduced thousands of pages of testimony from the 2005 and 2011 grand jury reports into that case. Prosecutors assert the transcripts demonstrate that Lynn frequently conspired with other diocesan leaders and sexually abusive priests to conceal their crimes and to reassign them, putting youngsters "in harm's way."

While Billy's case satisfies the state's complex formula for calculating the civil statute of limitations, questions of timing hang over the suit filed in March by the other victim in the criminal case. "Mark," now 29, has charged that Brennan raped him 1996 when he was 14. Brennan has denied it.

Mark's suit also claims that after he was hospitalized for a suicide attempt in 2006, the archdiocese's victim assistance office deceived him into handing over his medical and military service records, for use against him should he sue.

Contact staff writer David O'Reilly at 215-854-5723 or doreilly@phillynews.com.