Veteran Washington newsman Jerry Oppenheimer has started contacting people around town as he begins work on an unauthorized biography of Ethel Kennedy. It is not expected to be an easy job for him, since she is a private person who rarely gives interviews. Oppenheimer, whose recent book "Barbara Walters: An Unauthorized Biography" has had good reviews, said he signed a mid-six-figure advance with St. Martin's Press for the Kennedy book. It is scheduled for a spring 1993 publication.

Oppenheimer, who has been a reporter for the Washington Daily News and the Washington Star as well as a Channel 7 producer, said his working title is "The Other Mrs. Kennedy." He intends to examine her life since the 1968 assassination of her husband, Sen. Robert Kennedy. He said Kennedy has not responded to a letter he wrote her several weeks ago requesting an interview, but added, "I have my fingers crossed." Oppenheimer will write the book, however, even if she refuses to talk to him. Barbara Walters did not talk to him. Out and About Sightings Around Town: Fame is fleeting. Brooke Shields hasn't made a good movie since "Pretty Baby," but she certainly isn't hard to recognize, especially after all those Calvin Klein jeans advertisements and Bob Hope specials. Saturday night, she showed up at I Matti, the trendy Italian restaurant in Adams-Morgan, with a date and was sent to the bar to cool her heels waiting for a table. The couple's reservation had not been in her name. Customers began noticing it was Shields, but the hostess wasn't certain. Still, just in case it was Shields, she soon gave the couple a good table. When the actress paid for the pasta with her credit card, with the name Brooke Shields clearly evident, the waiter even asked for and got an autograph for his daughter. No one seemed to know her date, described as "cute" with short blond hair and a tan. They left the restaurant holding hands in the Adams-Morgan night ...

President Bush and his family flew out to the ballgame last evening to watch the Texas Rangers, partly owned by one of the president's sons, take on the Orioles in Baltimore. The president left before the exciting ninth inning, which saw the Orioles walk to victory. Making the helicopter trip with the president were his wife, Barbara, sons George W., the Rangers' co-owner, and Marvin, and daughter Dorothy LeBlond, as well as several spouses and grandchildren ...

Maybe the attorney general just wanted to see what the actor looked like who was using his name. Dick Thornburgh showed up at the Uptown Theatre Saturday night, with the usual security, to see the summer thriller "Die Hard 2." This film, like the original, features an obnoxious television reporter who causes more harm than good, and his movie name is Dick Thornburgh ...

One of those heroes on the half shell wasn't so heroic this weekend. Michaelangelo, one of the Teenage Mutant Ninja Turtles, was arrested near Charlottesville after he was seen relieving himself by the side of the road. One shudders to think how that scene would have struck a young fan. The arrested crime-fighter -- identified as Leon M. Blake of Wilkes-Barre, Pa. -- was charged with driving under the influence of alcohol and gave his occupation as "Teenage Mutant Ninja Turtle," adding "Michaelangelo" as an alias. Blake or Michaelangelo missed his promotional tour stop because he spent the weekend in an Albemarle County jail. Or as the unimpressed arresting officer said, "Well, I guess it just goes to show that at 2:36 in the morning, Ninja Turtles should be home in bed" ...