Firing squads on the beach ushered in his reign. The soldiers who had led the coup and assassinated Liberia's President William Tolbert lined up 13 of his top officials in April 1980, tied them to steel poles set up on the shore,, taunted them and, before the press and a cheering audience of Liberians, shot them. Out of this bloodbath rose Master Sgt. Samuel K. Doe as head of state. He was 29, a lean-faced young man in fatigues.

Two years and four months later, Doe is here on a five-day working visit. Secretary of State George P. Shultz paid a call on him at his Washington Hilton Hotel suite Tuesday morning, President Reagan lunched with him at noon and Mayor Marion Barry gave him a key to the city.

Yet the vivid newsprint image -- a series of photographs of the executions won a Pulitzer Prize -- lingers in the American eye. Doe answers this matter-of-factly.

"If the coup hadn't succeeded," he says, leaning forward intently, "wouldn't I have been executed?"

A party in his honor Tuesday night at the Liberian Embassy was hardly distinguishable from one given only a few years ago for the late president Tolbert. Diplomats, businessmen, State Department officials, reporters and photographers gathered in the heavily carpeted living room of the Liberian ambassador, television cameras tapping against the pendants of a chandelier. Crisp-suited security men -- Liberian and American -- stood at strategic locations in the house. Guests chattered noisily and smiling women carried silver trays offering champagne in gold-rimmed glasses.

Doe arrived and sat on a gold couch in the ambassador's living room to receive guests. At 31, he looks strikingly young -- a smooth, calm baby face behind square-rimmed glasses. His stomach shows some paunch, though his arms are muscular. He wears neatly pressed denim pants and a blue sport shirt, more casually dressed than the other guests. He has dropped the "Master Sergeant" title. A simple "Head of State" or "Commander in Chief" will do. He points out that he is no president -- he was not elected.

After the reception, he returns to his spacious suite at the Washington Hilton. He sits on a sofa and members of his entourage sit by quietly, expressionless, watching "Father Murphy" on the color television. They look up silently when a reporter is escorted in by a security man. Then their glance returns to the set, and someone in the room turns down the volume for the interview. On a nearby table is a glass jar of jellybeans, a gift from President Reagan.

Asked again about the executions, Doe says, "It's the law of the country that people be executed for their crimes -- both political and economic." He grins slightly in puzzled amusement. "They were guilty of crimes. I didn't decide the punishment."

Tolbert's government had been called oppressive. The ruling class that Doe and his army threw out had long guarded their wealth and power in Liberia, believing those with property should rule. They were the "settlers," the minority ruling Americo-Liberian class, the descendants of the freed American slaves who founded Liberia in 1822. The indigenous population, known derisively as "the country people," are generally poor and make up the majority of the country's 2 million people. "If you were from a poor family, you would never go to the university," Doe says of the old regime. "You would never become a foreign minister." Doe, the master sergeant, was born to "country people."

"God said if you violated a law, the law deals with you," he says. "God said whenever your finger or arm bothers you or is sore, it is better to cut it off." He chuckles. "Look in your Bible -- St. John." He puffs on a Marlboro, his left hand bearing a gold ring with little stones that look like diamonds -- but that he says are not -- and another gold ring bearing the letters 'AS' which he says has no meaning. A gold-colored ballpoint pen is clipped neatly to his shirt.

"There's no easy way to get in power in Africa," he says soberly. "You have to do things you have no business doing."

At the reception for Doe, no one speaks of the violence that accompanied Doe's rise to power. "I'll only say that we knew every one of those people who were executed," says Ruth Bond, sipping champagne as she looks around the room. She and her husband, J. Max Bond, the founder of the University of Liberia, left Liberia 25 years ago.

"Some were students. I wouldn't say that I like or dislike the government. I think about the people in the country. I think the old Liberians and the new want to see everything shared. . . .

"I say, whatever's good for Liberia." She says calmly, "Liberia will always be close to the hearts of Americans who have anything to do with Africa."

Ask Samuel Kanyon Doe about his religion and he says, "I am a soldier man -- a Baptist. I attended Baptist schools." His parents were poor rice farmers, and he was born in Tuzon, a native of the Krahn tribe. The clipped sounds and cadence of his native language heavily accent his English. He enlisted in the army in 1969 and went to high school at night.

"I applied through the defense ministry to go to college," he says. "I was denied." He shrugs. "They said there were no sufficient funds to go to school. They didn't want to see country people be more educated than the rich people."

In the Army he started in communications school and worked his way up to master sergeant. On April 12, 1980, he became head of state.

"Being head of state, you need support from God -- the very first thing," he says. "We have a lot of problems. When you're head of state, everyone comes to you. You want to please everyone. A lot of people's lives depend on you alone. It's very heady." He smiles a little. "It's very hard to be a head of state. You have to have patience. People look to you for judgment."

In his first year in office, he was characterized as nervous and paranoid. News reports told of secret trials before military tribunals--Doe says this is false -- the "banning" of a student activist and the shutting down of Liberia's only independent newspaper for 10 days when the publisher, his wife, and nine staff members were jailed for printing letters critical of that banning. Since then, the harsh military rule has softened. The two-year curfew has been lifted, the last 19 of 400 political prisoners have been freed and Doe has set civilian government elections for April 1985. Liberia's ailing economy is a major concern right now for Doe and his regime.

Doe says that world observers watched Liberia with concern. "Of course, a lot of poeple were not sure where we were going," he says. "They didn't know if we would be a socialist country or a communist country. But we're paving the way for a democracy now."

"You could say he's grown tremendously," says U.S. Army Maj. Louis Perkins, who was stationed in Liberia from 1978 to 1980 and attended the ambassador's reception for Doe. "Since those first days, he seems more assured of himself and his ability to lead. He had the charisma, but he didn't really know about leading."

Says Doe, "There's no job that God will give you that he didn't feel you could do. If God didn't feel that I was fit to have this job, I would not have succeeded in the coup attempt."

Yet he was only 29. "I am the youngest leader in the world," he says simply, "so there's no one to compare me with."

He says he won't run in 1985. "I'll be tired," Doe says. "Five years as head of state is enough for me. Maybe I'll go back to farming."

As head of state, Doe and his wife and four children live in the presidential mansion. "When you're president," he says, "you have no private life. You go to sleep -- something important happens, they wake you up. There's no chance to rest." No vacations, either: "I haven't been on vacation since 1980." Still, every Sunday he plays soccer.

Despite some loosening of the military rule, Doe is very straightforward about what people can and cannot do. "Any military government does not allow political activity," Doe says, "until the civilian people get back to power."

But he claims no one should fear him: "The only people who were afraid were the people who ruled for 135 years," he says, lighting up another Marlboro.

He is asked about freedom of the press.

"We have more freedom of the press than you have in the U.S.," he says confidently. "If you write anything here that you're not supposed to write, they send you to court."

About public dissent: "Most of the time we allow people to disagree. We ask people for suggestions. Whenever citizens feel that a decision is not in the interest of the people, they can tell the ministers. We sit down and discuss things.

"If someone writes something that I think is bad wrong , I call him in and ask him why he does it," says Doe, "and warn him not to do it again." He pauses. "So far nobody's written anything bad about me," he says with a grin, "because I don't do anything bad."

Perhaps because everyone is afraid of him, it is suggested.

"No, no," he says in a low, comforting voice, shaking his head. "I am free to be written about."