12 Soviet Coup Plotters to Stand Trial in April : Russia: The treason case could yield new testimony on the conspiracy that briefly ousted Gorbachev.

A dozen men who stunned the world in August, 1991, by moving to restore hard-line Communist rule in the Soviet Union were ordered Tuesday to stand trial for treason starting April 14. The four defendants still in prison were freed pending the outcome of the case.

The trial, before a military tribunal of Russia’s Supreme Court, could yield new testimony on the conspiracy that ousted Soviet President Mikhail S. Gorbachev for three days and could answer lingering mysteries as to why it so quickly unraveled.

If it ends in guilty verdicts, the trial could also bring long prison terms or even death sentences for the 12 unrepentant coup plotters--aging Soviet and Communist Party officials who moved to halt the decline of central authority under Gorbachev, and, in their failure, destroyed the Soviet Union itself.

Maj. Gen. Anatoly T. Ukolov, chairman of the tribunal, set the trial date after poring over the 1,000-page indictment and supporting evidence in 145 volumes of documents and 150 hours of video cassettes. He rejected defense appeals for dismissal of the charges.

“The judge has decided that there is enough evidence to hold a trial,” court spokesman Victor A. Pavlenok said. “It doesn’t mean that all the evidence is there or that there are no errors in the evidence. Some mistakes will be corrected in the course of the trial.”

Ukolov also ruled that “the age of the defendants and the aggravation of their illnesses” justifies conditional freedom for now.

As a result, former Vice President Gennady I. Yanayev, former Prime Minister Valentin S. Pavlov and two key figures from the military-industrial complex, Oleg D. Baklanov and Alexander I. Tizyakov, walked out of solitary confinement in Moscow’s Sailors’ Rest Prison on Monday night.

Most of the defendants are in their 60s, and six of them were freed last year on grounds of poor health--heart attacks, ulcers, severe weight loss and other signs of stress. Two others, former Defense Minister Dmitri T. Yazov and former KGB Chairman Vladimir A. Kryuchkov, were transferred to hospitals; they remained under guard there until Tuesday’s ruling.

Under the terms of the conditional freedom, each defendant must remain in his city of residence until the trial.

The other defendants are: former Politburo member Oleg S. Shenin; army Gen. Valentin I. Varennikov; former collective farm leader Vasily A. Staroduhtsev; former Soviet Parliament Chairman Anatoly I. Lukyanov, and two members of Gorbachev’s KGB security detachment, Yuri S. Plekhanov and Vyacheslav Generalov.

Seven defendants were members of the State Emergency Committee, which announced on Aug. 19, 1991, that it had taken power in the Soviet Union after isolating Gorbachev at his Black Sea resort. But it was a half-hearted coup. Its leaders failed to take full control of the country, win over the military or crush civilian opposition.

Published material on the coup, from prosecutors and defendants, has left many questions unanswered: Why did the coup leaders fail to isolate Russian President Boris N. Yeltsin? Why did the KGB fail to cut communications to Yeltsin’s headquarters once it became the center of resistance? And why didn’t the army storm the Yeltsin headquarters?

Ukolov announced that trial testimony will be heard in open court before him and two military jurors. He said he will call about 120 witnesses, including Gorbachev.

In comments to reporters, the judge sounded impatient to bring an end to the case, which has been delayed several times by procedural confusion and the sheer volume of evidence.

“The court will not allow any procrastination,” he said. “The trial could have begun much earlier if both sides had been fully acquainted with the case during the preliminary investigation.”

Genrikh P. Pavda, a defense lawyer, said he was “surprised by the haste of the decision,” which came five weeks after the judge was assigned to the case. He was concerned about what he called the “limited” number of witnesses. He said the prosecutor had initially proposed calling 1,000 witnesses.

Yeltsin’s government, plagued by a failing economy and far less popular than it was after the coup, is also apparently eager to get on with the trial and to remove the defendants’ plight as a divisive political issue. Defendants’ wives and lawyers have held news conferences and organized rallies, calling attention to the prisoners’ diet of boiled oats and potatoes, failing health and long detention.

Even the coup plotters themselves have spoken out, defending their actions in interviews.

Though most Russians still condemn the coup, time has softened their desire for harsh punishment of the plotters. A survey of 1,080 Muscovites by the Russian polling agency Mnenie showed that in September, 1991, 25% wanted them to get the death penalty while 5% wanted no punishment. This month the figures were reversed: 2.4% for the death penalty and 32% for no punishment.

Andrei Ostroukh and Sergei Loiko of The Times’ Moscow Bureau contributed to this report.