What was going on when I was born?

Craig S. Crimmins was found guilty yesterday of murdering a violinist at the Metropolitan Opera House last July 23. The 22-year-old former stagehand remained impassive when the verdict was announced, but his girlfriend, Mary Ann Fennell, wept loudly. After Mr. Crimmins had been led away, she kept repeating, while sobbing and saying: ''They're wrong, they're wrong. He didn't do it.'' The jury of seven women and five men in State Supreme Court in Manhattan determined that Mr. Crimmins had killed Helen Hagnes, who had been performing in an orchestra for the Berlin Ballet, by pushing her down an airshaft in his flight following his attempt to rape her. Maximum Term 25 Years to Life

As investigators searched today through material taken from his home and car, a man held for questioning about the slayings of 28 young blacks denied any involvement in the crimes and accused the authorities and the press of slandering him. Wayne B. Williams, a 23-year-old black, was held through the night and predawn hours by the Federal and local authorities before being released without being charged. But a four-hour search of his belongings produced blankets, clothing, carpet samples and other articles that were being analyzed by crime laboratory investigators for fibers, animal hairs or any other trace evidence that might link them to any of the deaths, which have been recorded in the last 22 months. Mr. Williams, an electronics expert and broker of local musical talent, told reporters after he was released early today that agents of the Federal Bureau of Investigation had repeatedly accused him of the murders and had warned him, ''It's just a matter of time before we get you.'' 'I'm a Prime Suspect' ''I still think I'm a prime suspect,'' Mr. Williams said, and at another point said the press had ''ruined my reputation.'' An F.B.I. spokesman, William McGrath, said, ''We have no comment about any of his allegations.'' The developments of the past 24 hours, which follow almost two years of disappointments and frustrations, have the city dizzy with anticipation.

Despite earlier pledges to keep its tax legislation lean and simple, the Reagan Administration has engaged in a flurry of adding ''sweeteners'' to capture crucial votes. And now the Democrats, who will draft their legislation later, may try to match or improve on the most attractive parts of the President's new package. The prime targets of the legislative maneuvering by the Administration and the House Democratic leadership are the votes of conservative Southern Democrats and wavering Republicans who hold the key to victory. With his announcement today, the President drew the battle lines against the Democratic leaders in the House and set the stage for another showdown, probably late this month.

In preparing for the visit of Secretary of State Alexander M. Haig Jr. to China next week, the Reagan Administration is moving toward decisions that will give more of a military cast to Chinese-American relations. Specifically, according to American officials, there is strong pressure to remove China from the list of Communist countries subject to special export controls. This would allow for the transfer of military technology such as the engine and electrical equipment from the new F-16 fighter plane and for the sale of TOW antitank missiles. Common Anti-Soviet Front Sought A number of officials see this as a way of strengthening a common anti-Soviet front, but some also see the prospective offer as an effort to induce Peking to accept the sale of an advanced type of fighter plane to Taiwan.

The State Court of Appeals ruled today that New York City did not have to pay police lieutenants and sergeants who were given supervisory positions more money simply because of their new designations. The 4-to-3 decision by the court, the state's highest, will save the city about $30 million in back salary and pension pay, according to Alfred Weinstein, assistant corporation counsel. Mr. Weinstein said that the city was ''pleased by the decision'' and that it might serve as a precedent for an associated case involving 1,000 patrolmen detailed to work in the detective division who have brought suit for financial compensation for their work. Their suit could cost the city $26 million in back salaries and pensions.

The chairman of the Chrysler Corporation, Lee A. Iacocca, held out some hope today of a return to profitability in the second quarter. Relentlessly optimistic in his address to the annual shareholders' meeting here, near the site of the company's Newark assembly plant, he stopped short of flatly predicting a profit, but did contend that if interest rates moderated quickly there could be modest earnings for the period, which ends in less than a month. If so, it would be the first profit reported by the company in nine quarters, or since the final three months of 1978, when it earned $43.2 million. Chrysler has had losses of more than $2.8 billion since then.

While it is possible to see only one play at the Quaigh Theater this weekend, that would mean passing up dozens of other shows. Starting at 7 tonight, the theater, in the Diplomat Hotel at 108 West 43d Street, will offer a ''dramathon'' - 50 plays and 10 variety acts, one after another, nonstop for 54 hours, some of them new works, others revivals, some short, some long. It starts with ''Benny,'' a 15-minute comedy by Renee Taylor and Joseph Bologna about two loners who meet on a park bench, starring Frank Biancamano and Suszan Telcher. Then it continues with Dorothy Parker's ''Here We Are.'' Tom Stoppard, William Saroyan, Anton Chekhov, Peter Shaffer and Eugene O'Neill are just a few of the other playwrights represented. Tickets are $4 for one show, $10 for six hours, $15 for 12 hours and $25 for the whole lot through 1 A.M. on Monday. Reservations: 221-9088. ROSES ARE BIGGER IN BROOKLYN The Cranford Rose Garden at the Brooklyn Botanic Garden opens for the season today, and its inhabitants - 5,000 rosebushes in 900 varieties - look different from previous springs. It seems that the cold, lack of snow and last winter's dryness resulted in fewer but much larger flowers. In conjunction with the opening, an art show and sale is scheduled Sunday, 10 A.M. to 5 P.M., along the fence overlooking the Rose Garden and Cherry Esplanade. Information: 622-4433.

Occupied Sinai, June 4 - President Anwar el-Sadat of Egypt asked Prime Minister Menachem Begin today to halt Israeli attacks on Palestinian guerrilla bases in Lebanon and to place no deadline on diplomatic efforts toward a peaceful solution of the crisis over Syrian missiles in Lebanon. Mr. Begin immediately rejected the request on the guerrilla bases, arguing that pre-emptive attacks by land, sea and air were essential to Israel's security. But he agreed to give more time for Syria to withdraw the antiaircraft missiles it began moving into Lebanon April 29, the day after Israeli jets shot down two Syrian helicopters. Talks Held at a Strategic Site The leaders outlined their positions at a news conference after a 90-minute meeting in this Sinai settlement overlooking the strategic Strait of Tiran leading into the Gulf of Aqaba. The settlement is scheduled to be returned to Egypt next April under the peace treaty signed by Egypt and Israel in 1979.

The pound sank to $1.9385 at the close of European trading today, continuing its dramatic plunge against the American currency amid expectations of a cut in the price of North Sea oil and a belief that the current high level of United States interest rates would be maintained. As investors deserted the currency, the pound hit its lowest exchange rate against the dollar in more than two and a half years. The recent drop is the sharpest slide since 1976, when the International Monetary Fund was called in to help the ailing British economy. ''This is the first real bear raid on the pound in five years,'' said Roy Palmer, a foreign exchange specialist with Manufacturers Hanover Trust.

Governor Carey's transit advisory panel yesterday proposed a plan to finance Metropolitan Transportation Authority deficits with increases in the sales tax in areas served by the authority and in the statewide tax on oil-company receipts. It also asked for the creation of a new financial control board to monitor the agency. Under the panel's proposal, the sales tax - which is 8 percent in New York City and less in other areas - would rise by a quarter of a cent on the dollar. The tax on gross receipts of oil companies would rise from 2 percent to 3 percent next year.

Japanese leftists and unionists protest return of U.S. carrier A3 Reagan to attend North-South talks, Mexicans say A4 Acting President of Bangladesh pledges election on schedule A5 Around the World A7 Polish union votes brief warning strike for next Thursday A9 Government/Politics Harrisburg having trouble with crime and exodus A10 House panel approves plan to speed nuclear plant openings A12 Suspended sheriff asks Carey to investigate DelBello B2 Esposito running his mayoral campaign on a shoestring B3 City defers hiring firefighters until pension fund is approved B6 New York explores buying the 160 buses it has leased B16 General Around the Nation A10 Atlantans changing summer plans as fear continues A12 Jersey riparian rights costly to casinos B2 Rockefeller leads business group from city to Washington B3 Nine indicted in drugs and murder case B6 Education/Welfare Religious groups back tuition tax credits at hearing A13 Reagan proposals criticized at Harvard's commencement B4 City University confers advanced degrees on 236 B4 N.Y.U. holds 149th commencement exercises B4 Features/Notes Man in the News: Roy L. Williams, teamsters' president A11 Notes on People C23 Weekend Weekender Guide C1 Irish Fair in County Kings C1 Park storytelling marks 25th year C6 Theater: Broadway C2 "American Buffalo" at Circle in the Square C3 "The Meehans" at New City C13 Dance: Tchaikovsky Festival for City Ballet C1 Ethnic dance program in Queens C26 Screen: Films on New York at Modern Museum C5 At the Movies C8 "The Sea Wolves" opens C8 "Alligator" reviewed C12 "Cheech & Chong's Nice Dreams" opens C14 Music: Chamber views of Schu- bert and Bartok C3 Seaport opens Summerpier jazz series C15 LA Four at Fat Tuesday's C15 Art: African works at Met Museum C18 New European art on view C19 Auctions C20 Art People C22 Books: Publishing C24 "The Parachutists" by Edward Klein reviewed C24 "Best Seller" by Geoffrey Bocca reviewed C25 Restaurants C16 TV Weekend C27 Style The Evening Hours A16 "Reverse commuting": Going against the flow A16 A shopping showcase A16 S-a-r-c-o-p-h-a-g-u-s spells first prize A16 Obituaries Caroline Hood Carlin, ex-Rocke- feller Center executive B6 Sports Aoki posts 67 for one-stroke lead at Atlanta A18 Cosmos and Sao Paulo tie, 2-2 A18 Princeton's Wolf brings large talents to N.C.A.A. track meet A18 Yanks rout Orioles, 12-3, and sweep series A19 Chris Evert Lloyd and McEnroe are beaten in French open A19 Pleasant Colony draws outside post in field of 11 for Belmont A19 Judge to rule next week on injunction request in baseball dispute A19 Rangers expected to undergo a transformation under Brooks A19 Victories over Phils provide confidence for Mets' Harris A20 Bonds, called up by Cubs, injured on first play to him A20 George Vecsey on Clyde King, reluctant trouble-shooter A21 News Analysis Hedrick Smith discusses President's tax strategy A1 William Borders assesses outlook in Bangladesh A5 Editorials/Letters/Op-Ed Editorials A26 Denying the mentally ill The crime of scientific zeal Walter Mitty in the classroom Topics: dubious economies Letters A26 Tom Wicker: the spirit of Proposition 13 lives A27 Flora Lewis: the Polish factor and the West A27 N.E. Wilson: my town needs the MX A27 Robert L. Schuettinger: Lefever is fine A27

International Egypt sought to ease the crisis in Lebanon at a meeting in the Sinai. President Anwar el-Sadat asked Prime Minister Menachem Begin to halt Israeli attacks on Palestinian guerrilla bases and to place no deadline on diplomatic efforts for a peaceful solution of the dispute over Syrian missiles in Lebanon. Mr. Begin insisted that the attacks were essential to Israel's security, but he agreed to give Syria more time to withdraw the missiles. (Page A1, Col. 1.) The sale of advanced weapons to China is being considered by the Reagan Administration as it prepares for a visit to Peking next week by Secretary of State Alexander M. Haig Jr. Administration officials said there was rising interest in providing China with such technology as antitank missiles and the engine and electrical equipment from the new F-16 jet. (A1:3-4.)