BOSTON — A former parishioner at a Massachusetts church has filed a lawsuit alleging he was sexually abused as a child more than 30 years ago by a Catholic priest who is now an auxiliary bishop in the Archdiocese of Detroit.

The plaintiff, identified in court documents as John Doe No. 12, was a 12-year-old parishioner at Saint Mary of the Sacred Heart Parish in Lynn in 1989 and 1990 when he was sexually assaulted about 25 times by Paul Fitzpatrick Russell, according to the lawsuit filed Monday in Boston.

The Archdiocese of Detroit in a statement said Russell denied the allegations.

“Abp. Russell is shocked and saddened by the claims that have been made,” the statement said. “He states that the allegations are totally without merit and that his conscience is perfectly clear.”

Russell has been placed on “limited” ministerial duty, and Detroit Archbishop Allen Vigneron has pledged “complete cooperation.”

The suit also names as defendants the Archbishop of Boston and Russell’s supervisor at Saint Mary of the Sacred Heart.

“Given it is a pending legal matter we will withhold comment at this time,” a spokesperson for the Archdiocese of Boston said in an email.

The suit seeks a jury trial and unspecified damages.

Russell, who was ordained in 1987, went on to become priest-secretary for the late Boston Cardinal Bernard Law, joined the Vatican’s diplomatic service where he served as the church’s top ambassador to Turkey, Turkmenistan and Azerbaijan, and was named auxiliary bishop in Detroit in May.

The plaintiff met Russell when he volunteered at the parish food bank, according to the lawsuit. Russell invited the boy back to the parish rectory where he “began to groom him” before sexually assaulting him, the suit said.

The man turned to alcohol and drugs as a coping mechanism, considered suicide, sought mental health treatment, and still experiences flashbacks as well as feelings of guilt and shame, according to court documents.

He “did not understand he had been harmed by the conduct of the defendants” until 2021. He wishes to remain anonymous because he thinks making his name public “will cause him to be stigmatized, affect his personal relationships, and further harm him emotionally,” according to court documents.

The plaintiff, now in his mid-40s and living outside of Massachusetts, was inspired to come forward by others who have reported allegations of abuse that occurred decades ago, said his attorney, Carmen Durso.

“The age at which people have been coming forward has been getting lower, and mostly it’s because they have heard about other people coming forward, and that has given them the courage to talk about this,” he said. “It’s not so overwhelmingly shameful as it was before.”

Durso said to his knowledge Russell has never before faced abuse allegations.

According to the lawsuit, church officials in Boston have for decades hidden sexual abuse by priests, conspired to keep the information from becoming public, and protected suspected priests from criminal prosecution.

Boston became the center of the Catholic clergy abuse scandal that spread worldwide when The Boston Globe published a series of Pulitzer Prize-winning stories that showed priests suspected of abuse had been transferred from parish to parish without alerting parishioners.

The stories were the basis for the 2015 movie “Spotlight,” which won a Best Picture Academy Award.

The Survivors Network of those Abused by Priests, a church accountability and victim support group, called on the church to release its records on Russell.

“Given Bishop Russell’s high position in the Catholic church … we believe true transparency and accountability will only come when the files on the clergyman held by the church are publicly disclosed,” the group said in a statement.