Friends and relatives of Mary Ellen Schneider, a Bethesda woman thought to be teaching in Iran, were listening to news broadcasts for word of her over the weekend when they were shocked to hear that she had been in prison but escaped in a mass breakout during the fall of the government Sunday.

Schneider, 43, a professor at Tehran University, was widely quoted in news accounts yesterday from Tehran, as she fled along with 11,000 other prisoners, including Americans and Europeans, who hacked and clawed their way to freedom Sunday.

"We hadn't heard from her in about six months, and then everything sounded great," said Silvan Chiarizia, Schneider's brother-in-law, in Glenn Dale. "It's very mysterious.'"

State Department sources late yesterday said that an anonymous tipster informed the U.S. Embassy in Tehran three weeks ago that an American woman was in the Gasre Central Prison.

The sources said U.S. officials visited the prison on Jan. 18 and talked with Schneider, who said she had been jailed Dec. 27 and that she did not know the charges against her.She also requested that her next of kin not be notified. State Department sources said they had no further explanations of the incident.

Schneider told reporters Sunday the reason given her for her arrest was that a man had fallen off the roof of her apartment house.

U.S. officials in Tehran filed a protest against the failure of the Iranian government to notify them of her arrest, State Department sources said yesterday. Once freed Sunday, Schneider contacted the U.S. embassy to say she was safe, "but that's all we know," a State Department spokesman said.

"I can't believe she was involved in any political activities," said Martha Bell of Gaithersburg, a friend of Schneider's since 1963.

Schneider's friends and relatives said they had received only sporadic correspondence from her since she went to Tehran nearly two years ago as a translator with a firm that sold helicopters. She later became an associate professor in linguistics at the university.

Bell said the last she heard from Schneider, she was teaching methods of research and advising students on writing these and dissertations.

Schneider was fluent in German and had taught German at several Washington area colleges and English to foreign students, including Iranians, before going abroad.

Schneider had held positions at Catholic and American universities, Montgomery College and in the Montgomery and Fairfax counties' public schools, friends said.

She grew up in the Washington area and has a sister here. Schneider was divorced many years ago and has no children according to friends.

She loved to travel and to "see the world" and had taught in the 1960s in Germany, according to her friends.

Bill said that she last wrote Schneider about a month ago but the letter was returned. "I just assumed that because of all the trouble they weren't allowing letters in," Bell said.