During the summer months, he sat outside the Mount Carmel Roman Catholic Church in the Bronx and befriended young people in the predominantly Italian neighborhood. In clerical garb, he spoke to them in the erudite words of the Jesuit priest he claimed to be and in the gentle tone of one capable of infinite compassion.

"He spoke about God and religion like he was a real priest," said Gina Demalijaj, a church employee.

Yesterday the man, who called himself Father Giustino Visconti and said he taught canon law at nearby Fordham University, was arrested and charged with criminal impersonation and grand larceny.

In the last five years, the police said, the man -- whom they identified as John Fortune, 35, an unemployed man with no religious training -- performed a baptism, said as many as five Masses and heard confessions in the Fordham section of the Bronx.

In addition, the police said, he bilked a 52-year-old widow, a mother of three, of her retirement savings.

Mr. Fortune's double life came to an end yesterday afternoon when the police stopped him near his apartment and handcuffed him, in his priest's clothing, on the corner of East 196th Street and the Grand Concourse.

It began at least five years ago, when Mr. Fortune met the widow through a mutual friend, Police Capt. John Creegan said at a news conference last night. The widow, a mother of three who retired as a kitchen helper at a home for the elderly, turned to Mr. Fortune for guidance. Mr. Fortune gradually became a part of the family and began investing the widow's retirement savings -- $12,000 in all, the police said.

Meanwhile, about four years ago, Mr. Fortune became a well-liked fixture at Mount Carmel at 627 East 187th Street, where he introduced himself to the pastor as a visiting priest from Fordham and was invited to say Mass, Ms. Demalijaj said. But Mr. Fortune stumbled and made mistakes in the liturgy, she said, raising doubts about his background. Though the pastor did not report him to the police, Mr. Fortune was no longer asked to say Mass, she said. Still, he continued to visit the church until last year.

With his initial success in his impersonation, Mr. Fortune apparently grew more confident and reckless, the police said. Early this year, at a small chapel, he baptized a baby. But the parents began to suspect an impostor when their repeated requests for the baptismal certificate were not met.

The widow, meanwhile, had heard rumors that he was an impostor. She finally believed them last June, Captain Creegan said, after she asked him to perform her son's marriage -- and Mr. Fortune canceled at the last minute.

Mr. Fortune, who the police said had apparently not held a job in years, told a detective who arrested him that he had studied philosophy in Rome for three years. "He seems to be a wanna-be priest," Detective John Scianimanico said.

Photo: A man the police identified as John Fortune was chargedyesterday with impersonating a priest. (G. Paul Burnett/The New York Times)