The police showed up two days after a Catholic clergyman at a church near the Nicaraguan capital Managua delivered a Sunday sermon in May that included a prayer "for our priests."
The officers played an audio clip of the prayer and warned: These kinds of things are dangerous, recalled a priest who was at Sunday services and when the police officers arrived. He asked not to be identified for fear of arrest.
"We tried to explain that this is just normal prayer, nothing to do with politics," the priest said in a video interview. "But they already have proof against us that they can manipulate however they like."
Nicaraguan President Daniel Ortega's five-year campaign against the Catholic church has intensified since February, according to interviews with five priests inside and outside the country.
The priests, one in Nicaragua and four outside the country, describe a sharp increase in church surveillance by police and citizen informants; police beatings; arrests and expulsions of priests and nuns as well as seizures of church-owned properties.
This week's brief release of Nicaraguan Bishop Rolando Alvarez raised hopes for a turning point. But while senior Mexican Bishop Ramon Castro said in an interview that talks between representatives of the Nicaraguan government and the church are "undoubtedly" ongoing, he held out little hope of a breakthrough. "It's very probable," the Vatican diplomat said, "that we're going to have to pass through more difficult moments."
The escalation continued in March after Pope Francis condemned Nicaragua's government as a "gross dictatorship" and Ortega responded by severing ties with the Vatican.
The police referred questions to Nicaragua's foreign ministry, which did not respond to requests for comment. Vice President Rosario Murillo, the government's spokesperson and Ortega's wife, did not respond to written questions.
A Managua-based diplomat, who spoke on the condition of anonymity, said he had heard reports of police surveillance of clergy and found them credible.
He said he was concerned that the crackdown appeared ongoing, with credible accounts of an increase in expulsions of religious orders and property confiscations in addition to surveillance.
Vatican officials have told Reuters privately that they see the conflict in Nicaragua as one of the worst since the Cold War, when many communist countries in Eastern Europe persecuted the church.
In February, Bishop Alvarez, an Ortega critic, was convicted of treason, stripped of his citizenship and sentenced to 26 years in prison, without a trial.
The sentencing statement said Alvarez was, "the author of the crimes of damaging national integration, propagation of false news through information and communication technologies, aggravated obstruction of functions and disobedience or contempt of authority."
Alvarez denies the charges.
The bishop of the rural Matagalpa diocese was returned to prison on Wednesday after talks broke down over the terms for his release and that of other jailed clerics, a diplomatic source told Reuters.
In late May, the Nicaraguan government launched a money laundering investigation into the church, ordering the country's bishops and senior leader, Cardinal Leopoldo Brenes, to turn over financial documents and freezing all church bank accounts.
The freeze on accounts has made it difficult to buy food and other necessities for parishes, all five of the priests Reuters interviewed said. The government stepped in last month to pay teacher salaries at hundreds of church-affiliated schools.
Brenes has not commented publicly on the inquiry and his office declined Reuters' request for an interview.
A Vatican official, speaking on condition of anonymity, called the money laundering accusations "absurd."
At least four priests have been placed under house arrest since May 23, according to Martha Patricia Molina, an exiled Nicaraguan researcher and lawyer now living in Texas.
Seven priests have been expelled, six priests have fled the country, while two others have been denied re-entry so far this year, according to Molina.
A group of Brazilian nuns from the diocese of Leon were ordered to leave the country in June, according to text messages reviewed by Reuters and a post on their Facebook page.
The Nicaraguan bishops conference did not respond to a request for comment.
Late last month, Brazil's President Luiz Inacio Lula da Silva met the pope in the Vatican and pledged to personally lobby Ortega to free Alvarez, offering to open a communications channel between the Vatican and Managua.
The Nicaraguan government did not respond to questions or requests for comment.
The priests describe heavy surveillance of church services by police or civilian members of government-sponsored community councils, especially since Easter.
Three of them say they believe phone calls are being monitored. They did not provide proof and Reuters was unable to verify their claim independently.
"My mother told me yesterday that police arrived at our house and made everyone turn over their phone numbers," said one of the priests, currently outside the country. "It's an open secret that many people have their phones tapped."
Ortega's campaign against the church started five years ago after Catholic leaders were asked by the government to help mediate mass anti-government protests triggered by government plans to cut old-age pensions.
At least 356 civilians were killed in the protests, according to the human rights commission of the Organization of American States.
Ortega, 77, came to power in 1979 after deposing a right-wing dictatorship. He launched an offensive against the church in the 1980s, but after his electoral defeat in 1990, he made overtures to Catholics and backed an abortion ban.
His latest restrictions seem aimed at silencing priests, Erick Diaz, 33, a Nicaraguan priest in exile in Chicago, said.
"Priests inside Nicaragua must be silent. They can't even mention the name of the bishop because the police will come after you and they can put you in jail or force you into exile," he said.