At 6:30 a.m. on July 3, an early morning jogger found the battered body of Wen-chen Chen, a highly regarded professor at Carnegie-Mellon University here, beneath a fire escape on the campus of the National Taiwan University in Taipei. He had 13 broken ribs, a broken spine and numerous internal injuries.

Chen's family had last seen him 22 hours before when he was taken away by the Taiwan Garrison Command, the national security police, for questioning about his political activities in the United States. According to the official Taiwanese account, Chen was interrogated for 13 hours about letters, speeches and phone calls he had written or delivered in the United States, escorted part way back to his romm, and later committed suicide rather than face jail for his criticism of the ruling Taiwan regime.

Carnegie-Mellon University president Richard Cyert believes differently. "The police got over-enthusiastic in their treatment of Dr. Chen and overdid the violence," he said.

The mysterious circumstances around Chen's deaath have spurred a congressional investigation, widespread fear among Taiwanese in this country, and a disturbing set of questions with serious international implications:

Was Chen murdered for his political views in the United States? Is the Taiwan government conducting a fair investigation of the case? Were government security forces responsible for Chen's death? And, does Taiwan maintain a network of informers on American campuses to spy on activities of their countrymen?

Taiwan President Chiang Ching-kuo has pledged an intensive investigation of the incident, and prosecutors last week issued a 7,000-word report on the case. It said Chen, 31, fell from a fifth-floor balcony at the university library about 4 a.m., struck the edge of a second-floor balcony, and died.

"No evidence suggesting murder has been found thus far," the report concluded. "The death could have been an accident or suicide."

Hardly anyone here where Chen lived and worked for the last three years believes that, and the State Department, through the American Institute in Taiwan, has informed the Taiwan government that the report is unacceptable.

Chen, a statistics professor, had everything to live for, his former colleagues claim. He was young, bright and energetic. He had a good job, a wife, a new home and a year-old son. He had been given a three-year teaching contract before he left for a visit to his homeland.

"He's not the kind of person to commit suicide," says his neighbor, ydr. Joseph Mallova, a young physician. "He isn't the type to get despondent or depressed about anything. It isn't in his nature."

The incident has also split this city's small Taiwanese community into rival camps along ethnic lines. Half, most descendants of those who fled the Chinese mainland in the late 1940s, have condemned Carnegie-Mellon president Cyert for pressing for an investigation. The other half, most Taiwanese natives whose families have lived on the island for hundreds of years, are scared to death.

ythere's nothing new about allegations of human rights problems in Taiwan, a nation that has lived under martial law for three decades. But Chen seems like an unusual target.

He was husky, athletic man who lived quietly in a $70,000 red brick house where, according to neighbors, he could be found evenings in the back patio reciting Chinese nursery thymes to his son, Eric.

It was because of Eric that Chen decided to return to his home in Taiwan. Originally, just his wife, Sujen, was going. But as the weeks approached for departure, Chen decided to go along so the couple could present their first-born son to Chen's parents in a traditional ceremony before the family's ancestral shrine.

There was nothing to fear, Chen told skeptical friends. "I won't say anything about the government."

Chen was a native Taiwanese, whose family had lived in Taiwan for generations. He shared a feeling of many native Taiwanese that the ruling Kuomintang regime, controlled by officials who fled the Chinese mainland in the late 1940s, should share its power.

"We all understood his political views. He wanted to see more representation of Taiwanese natives in the government.He just hoped for more democracy," said Dr. Morris DeGroot, a fellow statistics professor. "But it couldn't have been a consuming passion of his, or some of his colleagues would have known about it. . . ."

He was, by all accounts here, a political moderate who came to the United States in 1975 and had been in enmeshed in academic life since. He earned masters and doctorate degrees in statistics at the University of Michigan. "He was an outstanding student, the best that I'd seen in statistics in 21 years," recalls his old adviser, Bruce Hill.

Chen joined the faculty of Carnegie-Mellon here in 1978 as an assistant professor. "He was generally regarded as one of the bright young researchers in his field," says DeGroot.

If Chen were a political activist, he was a secret one. Spokesmen for the militant Taiwanese independence movement, which favors an overthrow of the government, insist they had never heard of him before his death. His friends are aware of him making only one political speech and that was in 1979. And his only claim to community leadership was a stint as secretary-treasurer of the Pittsburgh chapter of the Taiwan American Association, a group that sponsors pot-luck suppers and softball games.

The initial reports after Chen's death supported these accounts. The Taiwan Garrison Command said Chen hand't been involved in any activities serious enough to bother it. It claimed the "interview" with Chen was friendly and he had eaten lunch and dinner with his interrogators.

But later the command presented a far different picture of his activities. Garrison Command officials said they had confronted Chen with photocopies of letters he had written to a well-known dissident, and tape recordings of speeches and phone calls he had made in Pittsburgh.

The letters, along with five checks of $1,000 each, were allegedly written to Shih Ming-teh, now serving life imprisonment for anti-government activities, at a time when he was manager of Formosa magazine.

Taiwanese newspaper have also quoted Gen. Wang Ching-hsu, a Garrison Command official, as saying" it is almost positive" Chen committed suicide because he was "sure he was going to prison."

Officials say after 13 hours of interrogation, Chen, healthy and unharmed, was taken to the apartment building where he was staying, dismissing his escorts after they'd taken him only half-way up to his fourth-floor apartment. Chen surfaced a couple of hours later at the home of a former University of Michigan roommate. There, according to an account in Taiwan's United Daily News, he raided the refrigerator, say down and wrote a letter. He said he feared he would be jailed, but "he didn't give any hint of suicide," the newspaper said.

Four hours later, he fell from a fifth-floor balcony at the university library, struck the edge of a second-floor balcony and was killed, according to officials.

Chen's former colleagues don't believe accounts of his death. They doubt that he was ever involved in any activities that would warrant imprisonment, or that he would have been able to scrape up $5,000 from his salary (assistant professors are paid about $25,000).

What happened in Pittsburgh after his death is far clearer. A student staying in Chen's home moved out because "he was afraid," recalls neighbor Karen Mallova. "He left because he feared he'd be linked with Chen. He even asked us to take his garbage because he was afraid government spies would go through it."

Taiwanese were reluctant to get involved in Chen's memorial service. They were unable to get a single student to ask the university for a room for the services, or an adult to apply for a parade permit.

At the services themselves, many participants wore masks or paper bags over their heads to protect their identities. "Not even the chairman or the co-chairman of the Taiwan Association wanted to show up," recalls one friend. "Everyone has relatives back there and they're worred about what might happen to them."

The death, Rep. Jim Leach (R-Iowa) says, "sent a very chilling message to Taiwanese in this country." It also gave credence to allegations that the ruling Kuomintang regime has a "very extensive" network of spies on American campuses, said Leach. "We believe some of the agents are paid and some do it to curry favor with authorities." ythe House subcommittee on Asian and Pacific affairs will hold hearings Thursday.

Robert Hsu, a Taiwan government spokesman, said charges that his government maintains a spy network or in any way was responsible for Chen's death "are totally groundless," and "quite a bit off base."

"Our whole country is deeply saddened by this case," he adds. "If it was a case of suicide, the whole country feels great sorrow."

In addition, a group of 36 Taiwanese in Pittburgh has sent a letter to university president Cyert voicing support for the ruling Kuomintang. "The Chinese community is very much bothered by romors there are spies among us. We donht think it's true," said Yuan-Chin Hu, one of the signatories.

How then, did Taiwanese officials receive accounts of Chen's activities in the United States, he was asked. "It's possible that someone just wrote to the Garrison Command. They do it just on their own."

Other Taiwanese here look at it far differently. "Chen was outspoken, but he felt he hadn't done much. That's why he went home," said one fo his close friends. "That's what makes us all sleepless at night. The next one could be me."