From the time he joined the priesthood three decades ago, he seemed destined to become a star. As a confidant to two bishops and then as the erudite and clubbable pastor of two churches, Monsignor Kevin Wallin was a towering figure in the Roman Catholic Church in southwestern Connecticut.

Parishioners felt buoyed by his homilies. They hungrily signed up for his far-flung spiritual pilgrimages, flocked to church fundraisers to catch his melodious voice interpreting show tunes. He attended opera with a man who would become a cardinal and he himself appeared bound for a bishop's miter.

But then about two years ago, troubling questions began to be whispered. He acted odd. He was thinner. He walked stooped over. He was absent. Was he sick? Or dying? And then the spicy talk about suspicious men trooping in and out of the rectory.

Finally, last month's revelation. The priest was locked up, charged with dealing crystal meth.

At a time when priests from California to Delaware have been accused of loathsome deeds, the allegations against Wallin, the former pastor of the Cathedral of St. Augustine in Bridgeport, are of a notably different dimension: that he was a drug dealer and addict who was buying an adult novelty shop to launder ill-gotten proceeds, a priest who was cross-dressing and having sex with men.

The enigmatic double life of Wallin burst into public view last month after federal prosecutors announced that they had arrested him on charges of possessing and conspiring to sell drugs that could send him to prison for life. Now 61, he languishes in jail, having pleaded not guilty to behavior that many who know him find both twisted and ungraspable.

The Diocese of Bridgeport had forced Wallin from his position at St. Augustine in June 2011, after it was alerted to his dissonant behavior. His parishioners were told only of ambiguous personal and health issues. When he balked at accepting help, the diocese quietly stripped him of his priestly functions, but it said it was unaware of any drug dealing.

"What he did in the end was shocking and spiraled out of our control," said Brian Wallace, a spokesman for the diocese. "When we learned about it we took action immediately and forcefully, and regrettably, given how good a priest he was."

The lurid case is the latest in a string of tainted episodes for the Bridgeport Diocese, which was engulfed in the clerical sexual abuse scourge that has convulsed the Catholic Church. Last year, the Rev. Michael R. Moynihan, the former pastor of St. Michael the Archangel Church in Greenwich, was sent to prison for obstructing justice after being accused of spending church money on himself. In 2007, the Rev. Michael Jude Fay, from St. John Roman Catholic Church in Darien, was convicted of stealing $1.3 million; he died in prison.

Many particulars remain unclear about Wallin's tangled life, and his lawyer did not return calls. His fall seems precipitous. But colleagues said that his faith had been weakening for years under the imperatives of running a financially crippled church, and that he had long been sexually active with men. His drug use, they suspect, may have been more recent, and the final tinder that exploded his life. From the time Wallin arrived in 2002 at St. Augustine, the diocese said, the church, like many inner-city churches, was losing money, and the losses were deepening. The diocese was pumping tens of thousands of dollars a year into it.

A good friend of the priest said he looked like "a refugee from a concentration camp." One day she came to the church to help with paperwork and found that the electricity was shut off for nonpayment.

By April 2011, the diocese began hearing from church workers about his degeneration. "He seemed distracted, more ready to take offense," Wallace said. "He had nervous facial twitches."

Several people thought he might have Parkinson's disease, or was on the brink of a nervous breakdown. He would miss appointments. He was three hours late to preside at a wedding.

About the same time, one church worker told diocesan officials that parades of men were visiting Wallin at the rectory at all hours. The diocese looked into it, and, as Wallace said, "We heard enough to believe that he was engaged in sexual activity in the rectory."

That June 3, Bishop William E. Lori confronted Wallin, who did not entirely refute the revelations. Lori told him he had to resign. On June 12, the parish was advised he was leaving for health and personal reasons.

After his departure, church officials found a bag stowed in the rectory containing adult pornographic videos, sexual toys and leather masks, according to church workers.

Alarmed at the possibility of child pornography or child abuse, the diocese hired an outside lawyer. The diocese said Wallin was questioned and denied interest in children. An expert searched his computer, but found nothing related to children.

The diocese decided it had a priest who had committed a sin but not a crime. Lori granted him a sabbatical. The diocese hoped that with help, he could fix himself and resume at a new parish. It continued paying him a monthly stipend of about $1,400.

The diocese told him to get a medical evaluation. Months passed. "He was dragging his feet," Wallace said. "We were, 'Father, when are you going to go?'"

Finally, Lori ordered him to go. The diocese would not specify where he went, but someone familiar with the case said that he underwent an extensive examination at Johns Hopkins Hospital in Baltimore.

It found that he needed residential treatment to deal with psychological and emotional issues, including excessive narcissism and a penchant for sex. He also was suspected of using drugs.

But he resisted seeking care. On Oct. 7, Lori suspended his faculties, meaning he was not allowed to act publicly as a priest, a decision the diocese kept private.

On Oct. 31, 2011, Wallin agreed to check into St. Luke Institute, a psychiatric hospital in Silver Spring, Md., that treats Catholic clergymen and others. While there, according to some who know him, it was determined that he had been using amphetamines. He left the hospital against staff wishes on Nov. 4.

The next month, Lori told him that if he did not accept further treatment he could be laicized, and thus dismissed from the clerical state.

Again he dithered. A new year arrived. By now, according to authorities, he had changed professions. He had become a drug dealer. He was living in a snug apartment in a matter-of-fact two-story building in Waterbury. He also was renting the unit across the hall from him, where authorities said a confederate lived.

This was his new demarcated principality, where law enforcement officials said he sold crystal meth.

New York drug enforcement agents got on to him from a New York drug distributor who said he met the priest at a party in early 2012 and began buying from him. The man became an informer.

New York agents tipped off Connecticut agents, who enlisted help from the state police. An undercover officer, according to authorities, made six drug purchases from Wallin. Eventually, his phones were tapped.

Wallin planned to leave for London on Jan. 3 for 12 days. A longtime friend, who said she knew nothing of his drug life, asked him to go with her and another woman on an educational tour about espionage. On the day his plane left, the law was at his door.

Diocese officials said they were unaware of the investigation and did not realize he was in jail for several days.

"You looked at him like he was God, practically," said Charlie Hall, a Danbury parishioner who lives in a shelter. "But now you realize, he's just human, like all the rest of us."

On Jan. 22, dressed in a baggy orange jumpsuit, a subdued Wallin pleaded not guilty at his arraignment in a Hartford federal court. Prosecutors tabulated that he had grossed more than $300,000 from drug sales.

Elizabeth Maker and Vivian Yee contributed reporting, and Alain Delaqueriere contributed research.