Release caps week of wild rumors. Lessons from Daniloff-Zakharov affair.

The release of American journalist Nicholas Daniloff offers the opportunity for the United States and Soviet Union to get back to business as usual. Mr. Daniloff, accused by the Soviet government of espionage, left Moscow for Frankfurt, West Germany, last evening, the first stop on his way back to the United States. His departure capped a week of seemingly fruitless negotiation in New York and wild rumor in Moscow.

US officials here refused to give any details of the conditions of his release, and knowledge of Daniloff's departure was apparently limited to the top two or three members of the US Embassy here.

His release follows a fourth round of talks on the case Sunday between Secretary of State George Shultz and Soviet Foreign Minister Eduard Shevardnadze. Although both Mr. Shultz and Mr. Shevardnadze were noncommittal at the end of their meeting, senior officials of the US Embassy appeared to have wind of something first thing Monday morning.

Early on in the case, informed sources had suggested that Daniloff might eventually be released as part of a multilayered series of exchanges. They said Daniloff might be released first, probably without a trial. Then at a later date Gennady Zakharov, the Soviet UN official detained on espionage charges in New York, might be exchanged for a number of Soviet dissidents or for other Soviet citizens serving time in a Soviet prison for espionage on behalf of the United States.

[In New York, an informed source at the UN told the Associated Press that Mr. Zakharov also would be freed as part of an exchange. But President Reagan denied any exchange had been arranged. At press time, there was no indication that any exchange was in the works.]

Daniloff's arrest led to a deepening of the already strained relations between the US and the Soviet Union. Reagan administration officials regularly said the arrest had cast a pall over any chances of a Reagan-Gorbachev summit taking place. The Soviets retorted that Washington was deliberately blowing the affair out of proportion in an effort to find a pretext for canceling a summit.

Daniloff, who was soon to leave Moscow as correspondent of U.S. News & World Report, was arrested on Aug. 30 as he was saying farewell to a longtime Soviet contact. The contact gave Daniloff an envelope, which he said contained press clippings. Immediately after this, Daniloff was arrested by agents of the KGB, the Soviet secret police. The envelope was found to contain photographs of military equipment and installations and maps marked secret.

Daniloff and the US government maintained that he had been set up by the KGB in retaliation for the US arrest a week earlier of Zakharov. The Soviets denied this, claiming to have plenty of proof of Daniloff's guilt, and said that many Western journalists here work for the US Central Intelligence Agency. A recent hardening in Moscow's tone had led many observers to speculate that Moscow was planning to carry through on public pledges to bring Daniloff to trial. Daniloff, however, told colleagues that he would not cooperate with the court if a trial took place. After 13 nights in a KGB detention center, Daniloff was released on Sept. 12 into the custody of the US Embassy.

US-Soviet relations were made worse and the Daniloff case more complicated by Washington's demand two weeks ago that 25 members of the Soviet mission to the UN leave New York by Oct. 1 or be expelled. US officials maintained that the decision had no connection with the Daniloff case. The Soviets viewed it as indirect retaliation.