The climax of the Amtrak sleeping car siege in Raleigh last weekend came at 2:30 a.m. Monday when an unarmed FBI agent from Washington, Raymundo E. Arras, quietly walked forward and raised his arms outward in the darkness to a gunman crouching inside the train.

For an extraordinary moment the two men -- the lawman and his adversary -- grasped hands through the train window in a simple human act of trust that capped 33 hours of intense conversation in Spanish as Arras -- never revealing that he was a federal agent -- gained the gunman's confidence in an effort to save two child hostages.

At that critical moment, Arras recalled, he thought of tightening his grip and wrenching the man down through the window and out of the train compartment where the stench of a body dead for more than two days was overpowering. But what if he failed? Somewhere in there, Arras knew, the man had a submachine gun.

Arras kept iron control of himself: "I extended my hands and we shook hands, we grasped both hands a minute," he said in an interview this week. "I said, 'Hurry, let me have the baby!' He turned to get the kid. He said, 'Okay, here she is.' I took the baby from him in the blanket."

Hours later, at 5:45 a.m., the gunman was talked into a peaceful surrender by a New York lawyer -- officials would not identify him -- who had once defended the gunman in court and whom the gunman considered his "godfather." The siege had lasted for three days.

When Arras rescued 3 1/2-year-old Zulie Ramirez, her 9-month-old brother Juan was dead inside the sleeping compartment--apparently of dehydration after two days without food or water. The children's mother -- also the gunman's sister, according to police -- had lain dead inside the sleeping car since she was shot Friday morning.

The gunman, identified as Mario Evangelista Navas Villabona, 29, a paroled narcotics dealer from Colombia, was charged with murder. Arras, 39, the Hispanic agent in the FBI's Washington field office who talked Villabona into giving up the child hostage, is one of 300 agency men specially trained in hostage negotiation. In the interview, he gave a detailed account of the drama, including his recollection of the words he exchanged with the gunman. He said he established rapport with Villabona, playing on his guilt at the infant's death and building on his concern that the girl, too, might die.

As the drama unfolded around the cordoned-off railroad car, officials heard Zulie's heartrending cries via a super-sensitive microphone placed near the sleeping car door: "Ama, ama, levante, levante! [Mama, wake up!.]"

Arras and other FBI hostage negotiation specialists were not called until midway in the siege, which began Friday morning after shots rang out as the Miami-to-New York Amtrak Silver Star approached Raleigh.

When the train arrived, the car was detached and surrounded by police while the other cars continued to New York. Villabona, his two child hostages and the body of their mother were inside a small sleeping compartment at one end of the detached car. The door to the compartment was closed, and police were able to place the microphone and a small speaker on the floor of the passage outside the door so that they could communicate with Villabona.

Early in the siege they also placed milk and food outside the door, hoping Villabona would give it to the children whom police could hear crying in the compartment. At some point Villabona sprayed the door with machinegun fire. No one was hit.

Police tried to communicate with Villabona through a Spanish-speaking local official, but he had little luck and the call went out for the FBI experts. By 6 p.m. Saturday, Arras was at the police command post next to Villabona's railroad car and on the other side of it from the sleeping compartment. With him was Gary W. Noesner, another hostage specialist from the Washington FBI office, and agent Frederick Lanceley, who teaches the hostage negotiation course at the FBI academy in Quantico, Va.

"This is Ray. I'm here to help you. How are the children?" Arras began.

Villabona didn't answer. Arras talked gently in that vein for a while, then stopped for an hour. Then he tried again, continually emphasizing a concern for the children that he hoped Villabona might share.

This pattern of brief, hourly, one-sided communication continued until about midnight, when Villabona finally said, as Arras recalled it: "You no-good son of a bitch, stop talking to me. You're a no-good . . . bastard. You don't care about the children. You're lying."

At this point, Arras said, "I felt at least I had a dialogue going. I told him I did want to help, that my concern was for the children . . . . I kept talking. My voice was calm, firm, sincere."

It was clear to the FBI and police they were not dealing with a political case. There had been no demands. They began to think that this might simply be a man who had, through an act of violence, backed himself into a corner. They knew he was frightened, that he did not trust them--perhaps because of experience with police in other countries.

According to agent Noesner, the goal at that point was to gain Villabona's trust by "an act of good faith, to get him to take sustenance from us for the children. We looked at that as our initial hurdle."

Despite the profanities hurled at him, Arras said he kept up his gentle prodding: "Mario, Mario, this is Ray. How are the children?" These efforts were met by silence until early Sunday morning when Villabona said, "If you really want to help the children, I need some IV fluids." Villabona said the plastic tube from a container of intravenous fluid used in hospitals to sustain patients should be threaded through a bullet hole in the door so he and the children could suck from it. Officials believed Villabona was worried that they would poison food given to him but that they would find it hard to tamper with an intravenous fluid container.

The bullet hole was ragged and the tube wouldn't go through despite frantic efforts. Villabona interpreted the failure as bad faith and communication broke down.

By daylight Sunday official concern for the children was intense. A pediatrician on the scene listened to the noises of the children over the communication system and warned they could die of dehydration. The stench from the dead woman's body enveloped the command post a train car-length away. Flies descended on the area.

"I waited an hour, then I tried to pick up the dialogue," said Arras. "We could have put [the IV] in the front, but he didn't want that. We suggested alternatives." Nothing worked. Time passed. Then, at 2:50 Sunday afternoon, Villabona flung open the window and made a 10-second appearance. Police did not shoot him for fear of harming a child.

"It was the beginning of the end, our first major break," said Noesner. Conversation about food delivery began again and, finally, after many desperate attempts, a food bundle was passed through the front window.

"Eat, feed the children, I won't bother you," Arras told Villabona. He noticed that Villabona then began calling him "Senor Ray" -- a sign of respect.

By late Sunday night, however, they were desperately concerned about the children. Arras kept asking about them, and finally there came a terrible revelation.

"He said, 'The baby is dead. Don't worry about the baby, Ray. The baby's dead.' I was stunned . . . . He said, 'Yes, I woke up today and he was blue and stiff.'" Villabona blamed the officials for the death because they had failed to get the IV tube into the compartment.

It was a crushing moment. Keeping control of his impulse to scream in rage at Villabona, Arras turned and left the scene. "I returned an hour later. I told him, 'I have just made my peace with the Lord. I will not carry the responsibility of the death of that baby. The responsibility is yours.' I established his guilt. I wanted to pass the guilt onto him."

By then it was early Monday and Arras, feeling that his foothold in the other man's psyche was strong, pressed hard: "I said, 'I have just gotten from my knees praying for the soul of that little boy. Also I'm praying for the girl because she's going to die."

Villabona insisted the girl was well.

"Are you absolutely sure? I don't want the girl to die!"

"No, Senor Ray, she has eaten and drunk. She is all right." But Villabona's concern for the girl's health was clearly growing.

Then, through what Arras regards as a miracle, the girl complained to Villabona that her stomach hurt. Arras seized on this, insisting it meant she was about to die, passionately pleading that she be released.

"Will you meet me at the window and give me the [girl]? I will come unarmed."

Villabona agreed, and put his bare hands out of the window in a show of good faith. Arras walked forward, grasped his hands for a moment, and received the child. "He said, 'Okay, here she is.' I took the baby in the blanket. I had such a rapport with him . . . . "