In Washington's most elegant establishment, curly-haired Barry Paul Lobowitz was the portrait of a wealthy man. He wore expensive suits on his pudgy frame and Gucci shoes on his feet as he mingled with patrons at the chic Four Seasons Hotel or at the stately Jockey Club, where federal investigators say he endeared himself to single, professional women.

Lebowitz, 43, said he was a marketing representative for Bally Manufacturing Corp., the leading supplier of slot machines to the world's casinos. According to court records, he claimed at various times that he drove a Rolls-Royce and owned a Jaguar, that he had a law degree from the prestigious University of Chicago, owned 20,000 shares of Bally stock and a penthouse in Chicago.

Now, however, Lebowitz is a resident of the D.C. Jail, where he is, being held on a $25,000 bond, charged with false pretenses and operating an interstate fraud scheme in which he allegedly bilked people of more tha $14,000. Law enforcement officials allege that he is an accomplished "con-man" who used the stories he told the women to obtain money from them and their friends as be moved across the country.

In New York City, Lynn Miller, a 35-year-old college professor, said she met Lebowitz at the Oak Room at the Plaza Hotel, where she had gone for a cocktail with a women friend. Lebowitz was dressed "impeccably," Miller said, and he carried a gold cigarette lighter. Miller said he asked her for a date and they exchanged telephone numbers. Lebowitz entertained her lavishly for two weeks, Miller said in a telephone interview, and then he suggested that she invest some money in Bally stock, claiming that he knew the stock was going to split.

Miller, who now says she thinks Lebowitz might have thought she was rich becuase she wore a fur coat and drove an expensive car, said she gave him more than $1,000.

"And then he disappeared and I couldn't find him," said Miller, who eventually filed a complaint with the New York Police Department. Det. Frank Ahern of the 107th Precinct, who investigated the case, said yesterday that he recovered Lebowitz's "black book" from luggage that Lebowitz had abandoned at a Manhattan hotel. It had names from Boston to California, Ahern said.

Miller, meanwhile, said she also called Bally corporate headquarters in Chicago to try to find Lebowitz. There, Bally's assistant general counsel, Neil E. Jenkins, said yesterday that he has received at least 25 calls since February 1979 from people looking for Barry Lebowitz.

When the inquiries were transferred to his office, Jenkins said the callers would say, "Barry? And I'd say, 'No, I've got bad news for you. We don't have anybody here named Barry.'"

According to Jenkins, Lebowitz has never worked for Bally and never owned any of its stock. Lebowitz has pleaded innocent to the charges against him and is scheduled to stand trial July 7. His court-appointed lawyer, Enid Hinkes, said that her client contends that most of the money involved loans between friends.

Federal investigators say Lebowitz was in Washington in March 1979, met a Bethesda woman and began to date her. The woman introduced Lebowitz to a male friend who , according to the federal indictment, loaned Lebowitz $8,000 to invest in Bally stock. The transaction was made after Lebowitz's false claims that he worked for Bally and was coordinating installation of slot machines in a new Bally casino in Atlantic City, N.J., in the indictment alleged.

Within a few days after the money had been turned over, one investigator said, Lebowitz had disappeared.

According to the indictment, the following November and December, Lebowitz used false stories to obtain $1,300 from a woman he met at the Four Seasons Hotel. Later, the indictment said, he falsely obtained $2,000 from a man after claiming he could buy Sony color televisions from an Atlantic City hotel at discount prices.

Lebowitz was arrested in Washington in February 1980, but released from custody by U.S. Magistrate Jean M. Dwyer. Lebowitz showed up for a second court appearance, but Dwyer dismissed the case, saying there was no probable cause to turn the allegations over to a grand jury. The U.S. Attorney's Office took the case to a grand jury anyway, and the following summer an indictment was returned in the case, which is now being prosecuted by Assistant U.S. Attorney Charles H. Roistacher of the fraud divison. After continued investigation, Lebowitz was reindicted last November on additional charges that he falsely obtained another $1,085 from three other people.

Lebowitz was arrested and held without bond in New York City last month after Bally's Jenkins got yet another telephone call, this one from a woman who said her boss had met Lebowitz in Dallas and returned to New York with him.

Jenkins said he called the FBI.