The visit that Dennis O'Mara had been expecting came on Dec. 23, as he stood in the vestibule of a Santiago church distributing Christmas cards that asked for "a New Year without torture" in Chile.

"Two policemen came through the open door and said, 'Okay, come with us,' " recalled the Columban Fathers Catholic missionary priest. "I argued with them, 'Look, I'm not doing anything illegal. Look at this. Does it say anything about the police, the secret police, the military? Don't you want torture to stop in Chile?' "

The two carabineros weren't interested. Taken to jail, the priest was declared "a danger to the internal peace of the country," ordered summarily deported under emergency provisions of Chile's 1980 constitution and put on a plane for Miami.

The Chilean Catholic church, half of its male clergy foreign nationals, strongly objected to the Chicago-born O'Mara's expulsion. Three other foreign priests had recently been expelled and six weeks earlier, a day after declaring a state of siege, the government of Gen. Augusto Pinochet had banned from the country the chief of the church's human rights office, the Rev. Ignacio Gutierrez, a Spanish Jesuit. Gutierrez had been traveling in Europe at the time.

O'Mara, who recently spent 10 days here telling lawmakers, church groups and the State Department about the nonviolent Sebastian Acevedo Movement Against Torture in Chile, said the Santiago police did not mistreat him after his arrest in December for participating in a citywide action that took antitorture Christmas-card distributors into 50 Santiago churches.

Nor was he harmed, he said, in the course of four previous arrests since joining the antitorture movement in August 1983. Indeed, insisted a Chilean embassy official here, nothing that happened to him in Chile in December had anything personally to do with Father O'Mara.

"You have to understand that Chile is living under special emergency powers," said embassy political officer Alfonso Silva. "Political activities are not allowed. You cannot get special treatment because you are a priest or because you are a foreigner."

The use of torture by police and security agencies in Chile has been widely documented -- by such private groups as Amnesty International and Americas Watch and by public international bodies such as the human rights commission of the Organization of American States. The U.S. State Department, since 1981 Chile's most steadfast ally in international forums, has also acknowledged in reports to Congress that torture is a problem in Chile.

For 10 years, O'Mara, 48, taught social ethics to seminarians and worked with alcoholics at public shelters in Sydney, Australia, before being sent to Chile in 1978. In 1982, he succeeded two expelled foreign priests who had been working in Pudahuel, a working class and shantytown district on Santiago's west side containing about 250,000 people.

His involvement in the torture protest began the following August, when he was invited to attend an organizational meeting and to join about 100 others in a demonstration on Sept. 14, 1983, in front of the headquarters of the Central Nacionale de Informacion (CNI), the secret police. O'Mara, four other priests and five nuns were among 28 persons arrested in that protest, he said.

The name Sebastian Acevedo came later -- in November 1983, after the grief-stricken father of two youngsters arrested by agents of what looked to neighbors like the security police, being unable anywhere to learn where his children had been taken, set himself afire in the main plaza of the provincial city of Concepcion, several hundred miles from Santiago, and died seven hours later in a hospital.

"Before he died," said O'Mara, "Acevedo's daughter was released by the secret police, showing signs of bad treatment, and was with him when he died." The priest said he participated in 18 or 19 movement "actions" -- one every five or six weeks, with as many as 250 other protesters, during the 16 months before his expulsion. Besides the secret police headquarters, the group held processions in Santiago's cathedral square and vigils outside district police stations, the civil courts, the offices of the minister of the interior and those of El Mercurio, Chile's leading, loyalist newspaper.

"We went to the Mercurio," he said, "because the newspapers there are accomplices of torture." On such occasions, he recalled, the group would stand in the street outside the newspaper's offices chanting, in Greek-chorus fashion, "Eduardo Jara, student of journalism, was arrested and died of torture," with a chorus answering, "And the Mercurio does nothing."

The group had an "action" as well on the day in January a year ago when Chile honored its police -- "talking to them in the street, wishing them well, and saying, 'You know, you have a great tradition' and then adding, 'By the way, recently I've heard there's torture in some of the police stations. What do you think of that?' "

The police reacted to this action with "every possible response -- from appreciation, to rejection, to threats," he said.

One of O'Mara's purposes in coming to Washington was to formally waive his rights under the privacy act, which he failed to do when a U.S. consular official visited him in his jail cell two days after Christmas in Santiago. The State Department subsequently cited this omission in refusing to respond to requests for information about the circumstances of his expulsion, including one by Sen. Donald W. Riegle Jr. (D-Mich), on behalf of a constituent.

"I didn't want them to hide behind the fact that I didn't sign that waiver, and I was ignorant of the implications in not signing that waiver, in regards to U.S. statements," O'Mara said.

Last week, the priest visited the department's Bureau of Human Rights, where he presented a statement waiving his privacy rights to a group that included Deputy Assistant Secretary Gary Matthews.