MOSCOW, SEPT. 3 -- The prosecution built its case against Mathias Rust today, with a parade of witnesses decrying the West German pilot's swoop over Red Square as malicious and the chief prosecutor demanding that the Soviet Supreme Court sentence him to eight years in a labor camp.

One by one, Soviets who had watched Rust fly by the Kremlin in May said what they saw was not a stunt, but a provocation that had wreaked fear and risked lives.

Countering the 19-year-old Rust's opening-day decription of his flight from Finland to Moscow as a mission of peace, a policeman told the packed courtroom that the flight had put lives in danger. "Clearly," said Anatoly Buts, "it created a great threat to people's safety."

Rust opened his three-day trial yesterday with an apology and a rejection of part of the charges against him. Today, the prosecution seemed to lay the groundwork for a heavy sentence. The three-man jury is expected to decide the case Friday.

Rust flew from Helsinki May 28 in a daredevil five-hour flight through Soviet airspace that led to a senior military shake-up, including the dismissal of the defense minister.

Labeling Rust "a hooligan," chief prosecutor Vladimir Andreyev asked that he receive a sentence of eight years in a camp with a strict labor regime, the second most severe of Soviet penal institutions.

Andreyev specified how the sentence should be broken down according to the three charges against Rust, including eight years for violating international flight rules, four years for malicious hooliganism and two years for illegally crossing the border. Soviet law allows sentences to run concurrently.

"Although he is not yet 20," Andreyev said, "he understood that he was risking his own life and the lives of others.

"I underline that the law is the law in the Soviet Union as in West Germany," he added. "He is a hooligan."

Yesterday, Rust rejected the hooliganism charge but gave guilty pleas to the charges of illegally crossing the Soviet border and violating international flight rules.

The courtroom audience, including Soviet and West German officials and Rust's family members, remained solemn during the second day of testimony. Some 25 correspondents were invited to attend. This report is based on their accounts, and those of several West German diplomats.

From a wooden box in the center of the courtroom, six Soviet witnesses spent the morning session describing the reactions Rust evoked and the risks they said he had posed.

One Muscovite said Rust had flown "at a high speed" between Spassky Tower on the Kremlin wall and St. Basil's Cathedral in front of it. Another told of his low swoop just above Lenin's Tomb, the most revered monument in the Soviet Union. "My first reaction was to duck," policeman Andrei Molokoyedov said. "People were afraid," added Yuri Talyzin, a young man who had been walking along the square.

The chief prosecutor's main objective seemed to be to depict Rust as a hooligan, or hoodlum, with little respect for others. Andreyev called Soviet aviation expert Anatoly Brylov, for instance, who testified that 10 international passenger planes were descending toward Moscow's main airport as Rust flew nearby.

In a televised interview this evening, Brylov estimated that Rust violated flight regulations more than 50 times.

Andreyev also appeared to be portraying Rust as having acted in a calculating rather than spontaneous way. Under questioning, for instance, witness Yevgeny Trufanov testified that Rust had jumped out of the plane and started to tell his story. "I didn't see that he looked afraid," Trufanov said. "He was calm."

The judge asked Rust if he had told the people in Red Square that he was on a peace mission. Rust replied that he could not remember.

Building on the impression the witnesses had given, prosecutor Andreyev climaxed the day with a critical summary and a demand for stiff sentencing.

"I am Mathias Rust and I can land anywhere I want to land," Andreyev said. "What is Red Square for a Russian person, for our multinational country? It is a sacred place for us.

"The fact that he did not take into consideration the consequences and intentionally landed -- he is a hooligan."

Soviet media took a grim view of the case. The official news agency Tass used an interview with an American legal scholar to suggest that a similar case in the United States would bring severe punishment.

In another report, Tass criticized the defendant directly. "Rust has realized now that his thoughtless flight ended successfully only by chance. That is why he looked more serious today," it said.