When it was all over, she told me in perfect English that for more than two years her job had been to read whatever I wrote about Bolivia. She also warned me that I should be careful. "This," she smiled, "would be no way to end your career as a journalist."

That was about 8:30 Monday night, 2 1/2 hours after five Army intelligence agents, one of them armed with a submachine gun, arrived at my hotel in La Paz to take me in for questioning.

As I sat in the small interrogation room, faced by two inquisitors and a typist who kept trying to change my answers, I was told I was under arrest for national security reasons.

Bolivia has a civilian government with constitutional guarantees, and things such as this are not supposed to happen. But every day, this country is more of a police state; the military does what it pleases. Monday night it got around to me.

During the whole episode, which lasted nearly three hours, I was never threatened physically. The submachine gun was, however, pointed directly at my stomach during the 15-minute ride from the hotel to Army intelligence headquarters, and the interrogation room was equipped with torture apparatus. In a drawer, open so I could see, were the wires and clips of the picana, the common instrument of electric-shock torture, and placed prominently in front of me was a red-and-white case labeled "Bolivian Red Cross."

Only once did my inquisitors get angry. One officer, whom U.S. diplomats later identified as Maj. Villaroel, got very excited at one point and warned me that he was getting tired of my refusal to answer questions about sources for an article I had written last week about the political situation in Bolivia. In the article, I quoted informed observers predicting an imminent military coup.

I responded that if the major were tired of me, he could take me back to my hotel, since I had not requested this interview. He replied with an ominous smile. "Oh, no, you won't be going back to your hotel right away. After we're finished here, you'll be having dinner with us."

I understood what he was alluding to. Before leaving the hotel, I had grabbed a sweater from my room. I had assumed I would be spending the night somewhere cold.

When Villaroel arrived at my hotel at about 5:45 p.m. Monday, I was in the lobby on my way to the Telex machine to send the last part of an article about a government crisis that has developed here. The story was a follow-up to an article which had said the U.S. Embassy and Ambassador Marvin Weissman had been involved in attempting to thwart a military coup May 30.

The military high command had demanded Weissman's ouster from Bolivia, saying he had acted like an "imperial viceroy" and had "overstepped the bounds" of his diplomatic position by intervening against the planned coup. At the same time, the military denied that it had been planning a coup, and claimed that Weissman had done nothing to thwart it.

At the hotel, Maj. Villaroel first identified himself as a reporter with Aqui, a local newspaper, and asked to interview me. I asked him to wait 10 minutes, and by the time I returned to the lobby, Maj. Villaroel had dropped his journalist guise. He flashed a Ministry of Interior identification badge, and told me I was wanted for questioning.

I insisted on calling the U.S. Embassy before leaving. He insisted I come immediately, saying I could call the embassy once I got to the ministry. Four other men were now in the lobby, and other guests were discreetly moving toward the elevators. One of the receptionists quickly dialed the embassy number, and I managed to grab the phone and tell the marine guard who I was and what was happening before the mayor cut the connection.

He escorted me to a waiting jeep. Throughout the ride, a submachine gun was pointed at my stomach.

I had never been to the Interior Ministry before, but I knew when the jeep entered the heavily guarded compound that I had not been taken there. I was taken to a building identified only as the National Geographic Institute of the Army.

On the second floor of one of the buildings inside the compound, I was ushered into the office of a uniformed officer. He got right down to business."You wrote the article saying there was a coup planned in Bolivia. bYou're the cause of all the trouble."

I started to explain that the article simply reported what I had been told, but the officer wasn't particularly interested. He ordered Maj. Villaroel to take me away for questioning.

The major led me to the nearby interrogation room, where we were joined by the woman who would later warn me to be careful and the typist who would listen to what I said in Spanish, change key phrases, read back what he had written, and then get exasperated when I told him what he had written was not correct.

The officers wanted to know such details as when I had entered Bolivia; on which flight; who, if anyone, had met me at the airport; and where I sent my telexes. Then the central theme became clear. They wanted to know to whom I had spoken, specifically to which Bolivian politicians, to which journalists, to which foreigners. I kept waiting for the major to ask me if I had spoken to Ambassador Weissman.

But the question never came. Maybe because Villaroel was already angry, and realized he wasn't getting anywhere with his line of questioning. My standard response was, "For professional reasons, I cannot respond to that question."

The worst part was when he told me he was getting tired of me and that we would be having dinner together.

I did agree to describe the already published article I had written, although I suggested that the best thing for my inquisitors to do would be to ask their embassy in Washington for a copy. Neither the major nor the woman liked that very much.

The atmosphere began to change about 8 p.m., when a young cadet came in. Villaroel smiled and told me, "Your embassy is inquiring about you."

In fact, I later learned the embassy had moved very quickly. They were in almost immediate contact with the Interior Ministry, which denied that it had ordered my detention or knew where I was.

The embassy then demanded that the ministry find out if I had been picked up by one of the security services. By approximately 7:20 p.m., the Interior Ministry confirmed that I was in the hands of the Army intelligence.

By about 8:30 p.m., the inquisition was finished. I signed five copies of the typed transcript, reading each copy carefully and changing those parts the typist still had wrong. The last question was whether I had been physically-abused. I still didn't know if we were leaving for dinner or the hotel, so I responded that "as of now, I have not been mistreated."

The atmosphere suddenly became much more cordial. The officer who had ordered the interrogation came in smiling. He read the transcript and asked what may have been the question he really wanted answered: "Do you have any friends or sources in the military?"

"No," I said. "Unfortunately, I don't. I have asked for interviews with the military, but they have always been refused."

"Well," he said, "now you know where to come."