Jeffrey Cohen was a 21-year-old law student at Catholic University in 1971 when he bought a house on S Street NW for $24,000 and sold it six weeks later for $36,000. It was his first real estate deal.

In the decade that followed, Cohen, the son of millionaire oil distributor Norman Cohen and a close friend of Mayor Marion Barry, bought the National Bank of Commerce, purchased a Victorian-style home in Cleveland Park worth more than $512,000 and pursued a shrewd investment strategy occasionally helped by timely government intervention or assistance.

He has carved out a unique role as a white businessman with access to the District's predominantly black political establishment and forged alliances with community groups that hungered for a piece of the development game. Cohen often has operated on the fringes of the real estate industry, investing in the city's 14th and I streets NW red light district and other marginal areas.

Now Cohen is at the center of a complex and controversial $12.5 million land deal with the D.C. government in the Shaw neighborhood, and many in the business and political communities are wondering what he's up to.

Cohen, 35, says he has matured and wants to devote most of his energy to the worthy cause of restoring the Shaw area to its former prominence as a center of local black entertainment and commerce. He resigned as chairman of his bank last month and says he is selling off much of his property to pool his resources for the Shaw venture.

But just as Cohen has fascinated some with his successes, his latest venture has others suspicious that he might have been overextended in his real estate holdings and in need of a government bail-out.

"When you talk to Jeff you get a feeling he has a genuine social interest in the city," said D.C. City Council member Charlene Drew Jarvis (D-Ward 4), chairman of the Housing and Community Development Committee and one of the skeptics. "But he also has a driving interest in his bottom-line economics."

David Abramson, an advertising executive and a friend of Cohen, views the deal as a new and calculated phase in Cohen's career.

"Jeff is a terrific guy, one of the smartest guys I've ever met," he said. "What I like is he did it his own way. It's the Sinatra thing. He did it his own way and did it well."

Cohen's acquisition in 1978 of the former Children's Hospital site, near 13th and V streets NW in the down-and-out Shaw area, is probably the classic example of his talent for exploiting a seemingly useless piece of property.

He and his partners paid about $5 million for the abandoned site, saying they would convert it into a prominent medical rehabilitation center, with services and accommodations on a par with the Mayo Clinic.

Cohen's group, with the backing of the mayor and over the objections of some city health planning experts and others in the medical profession, obtained the necessary authority for the project from the D.C. State Health Planning and Development Agency in October 1982. But the center was never built in Shaw.

Instead, the group sold the hard-to-obtain development rights for the rehabilitation center to Washington Hospital Center a year later for $8.7 million. Washington Hospital Center undertook construction of the rehabilitation center at another site, near its main facility at 110 Irving St. NW, and the center is nearing completion.

Cohen's group received an additional $5.7 million from Washington Hospital Center to cover its architectural and legal fees and other costs associated with its development efforts.

In all, Cohen's group was paid $14.5 million not to build the rehabilitation center.

Last month, Cohen and his partners sold the old Children's Hospital property to the D.C. government for $5.8 million, about $800,000 more than they paid for it, as part of the overall deal to try to spur redevelopment in the blighted Shaw community.

"Sure it was a helluva deal, but we took a helluva risk, too," Cohen said last week in recalling the hospital transaction. "I mean, give me some credit for having found a way to create a rehabilitation hospital . . . . I think that's a pretty decent contribution to the quality of life in this town. The fact that I made some money doing that, you know, I don't think that's so terrible."

Cohen, a native of Washington who grew up in a Conservative Jewish family, has a shock of black hair and dark, expressive eyebrows. A craving for sweets has left him with a slight paunch.

Cohen has an engaging, low-key style, which some say belies a burning ambition and drive. His persuasive personality has been a major asset over the years, whether he was selling clothes off the racks at Hecht's, clerking for a D.C. Superior Court judge, buying real estate or negotiating a complicated bank acquisition.

"I've always found him to be aggressive, always selling his point of view," said former city administrator Elijah B. Rogers, another Cohen friend. "Sometimes I think he comes across as a little too pushy, but on the other hand that's the way you try to get things done."

He met his wife Francine in 1969 when he was a junior at the University of Pennsylvania and she was an incoming freshman. Cohen got himself assigned to welcoming new students at the university's only all-women's dormitory and immediately spotted his future wife, a former Miss American Teen-Ager.

"It was love at first sight," recalls Francine Cohen. They were married in New York in June 1973, settled in Washington and have two children.

Cohen practiced law briefly, but found the real estate business far more alluring and profitable. He became part of a group of cocky Young Turks in Washington's business community, taking chances that his more cautious father never dreamed of and reveling in his notoriety.

He publicly "syndicated" many of his real estate deals, bringing in limited-partner investors who sought both profits and a place to shelter their money. Banks looked more kindly upon Cohen's bank loan applications when he could furnish them with a list of equity partners.

"Jeff is a tremendous risk-taker," Francine Cohen explained. "He's going to shoot for it all and he doesn't take any compromise positions."

Theodore Mariani, an architect and one of Cohen's former business associates, said Cohen "has one of the sharpest minds you'll find in this town," but that he may have hurt himself by cultivating a public image as a wheeler-dealer.

"I think in some instances the tremendous amount of publicity has not done him all that much good," Mariani said. "People sometimes get a perception of a person from the newspapers that is not reality."

Cohen used a bank loan to purchase stock in the D.C. National Bank in late 1978. Eventually, he acquired a one-third interest in the bank before selling his stock and turning a $1 million profit.

By December 1980, the aggressive Cohen had obtained options to buy two national banks -- the Hemisphere National Bank, a minority-controlled institution, and the Bank of Columbia.

When some of the Hemisphere directors balked at the prospect of a non-Hispanic taking over, Cohen canceled the deal and purchased the Bank of Columbia, a small bank with assets that currently total $72 million. The bank's name was changed to Bank of Commerce in October 1981.

Today, Cohen says he has grown tired of the rat race of land deals and banking and plans to work full time with his wife and community leaders to make the proposed Shaw redevelopment a success. He said he has shed his three-piece business suits in favor of jeans and work shirt. As a symbolic gesture of sorts, he recently sold his classic 1971 Mercedes in favor of the family Jeep.

"If I can do something good and help bring that area back and do it the way that nobody's ever done anything before . . . that's what I'm turned on about doing," he said. "And I'll make money doing it. I'm not doing it for free. And I'll make a lot of money at the same time for the community people. That's kind of exciting."

As for the rumors that he was overextended and experiencing financial difficulty, Cohen said he has lived with similar speculation for years by his detractors.

"I think there probably are a lot of people out there who are jealous of what I've been able to accomplish or who I am associated with, whether its Marion [Barry] or others," he said. "A lot of people don't like the city government, don't like the fact I happen to have a lot of black friends that are real friends. So there will always be, I guess, folks who would like to be able to see me have a problem, financially or otherwise."

Cohen is sensitive to suggestions that his close friendship with the mayor may have paved the way for his frequent dealings with the city government.

The two men first met shortly after Barry was elected to the City Council in 1974. They argued over rent control, with Barry in favor of it and Cohen opposed, but gradually became good friends.

Cohen was among a small handful of businessmen, including lawyer Max Berry and restaurateur Stuart Long, who supported Barry for mayor in 1978 and helped raise campaign funds.

"Marion and I are more than good friends," Cohen said. "I think we're more like family. Marion is more like a brother than he is a friend."

Barry said he likes and respects Cohen and appreciates his commitment to the city, but speaks of their relationship in far less sentimental tones than does Cohen.

"We're both Pisces, which might account for some of the chemistry," Barry said. "I admire him in the sense that, I think when I met Jeffrey he was less than 30 and he appeared to be on the move businesswise. And I like people like that, who do something with their lives early.

"Plus he's not one of these underhanded, slimy, double-dealing business persons," Barry said. "There are some in this town who will do anything to make a buck. They're going to screw you, screw me, screw the city, screw everybody. He's not like that. That's not his philosophy; that's not his character."

Barry and his wife Effi have vacationed with the Cohens at Rehoboth Beach and on Nantucket. Barry and Cohen also traveled together to Israel in 1981 on a trip sponsored by a local chapter of the American Jewish Congress. Just before Barry's son Christopher was born June 17, 1980, the Barrys asked Cohen to be one of the baby's three godfathers. The mayor thought it would be good for Christopher to have a guardian from "a different culture or race."

Cohen chaired the 1983 Jewish National Fund of America dinner where Barry received the organization's Tree of Life Award. Only two other blacks, Martin Luther King Jr. and Mayor Tom Bradley of Los Angeles, have received the award, the group's highest.

Cohen has had extensive dealings with the city government. For years the city paid Cohen's Parkside Hotel, 1336 I Street NW, to provide emergency shelter to homeless families. Barry's support was crucial in winning authorization for Cohen's rehabilitation hospital project.

Also, the mayor's decision to build a new municipal office building at the northwest corner of 14th and U streets NW, over the objections of some high-ranking city officials, indirectly enhanced the value of Cohen's holdings in the area.

The city's recent purchase of those holdings has triggered speculation among some politicians and businessmen that the city was providing a favor of sorts for Cohen, who had been saddled with about $7 million in liens against the property. Plans call for Cohen and a nonprofit Shaw community group to develop retail and office space, 1,000 units of low-cost housing, and a performing arts center on the sites.

"Marion ought to be given a lot of credit for having permitted the city to permit the deal in Shaw," said Cohen. "It would have been very easy for him politically to say no . . . . [He] wouldn't have been reading about himself in the newspapers . . . linked to me."

Barry said at a recent news conference that he steered clear of the city's negotiations to acquire the Shaw property, and that he had been "shocked" to learn that Cohen actually owned all the land.

But in an interview Friday, the mayor indicated he had kept close tabs on the negotiations that led to the deal, and at one point suggested ways to end an impasse and shape the agreement. Barry was concerned enough to call from Africa last December to check on progress.

At the same time, Cohen has been selling off his other holdings, including three office buildings on Connecticut Avenue NW. He has contracted to sell the Parkside Hotel and four other parcels at 14th and I streets NW in the heart of the red-light district for about $12 million, or $2 million more than it cost to assemble the sites.

"I'm selling those properties which I have responsibility for in terms of their operation or development," he said. "I've got too many worries and problems in developing" the Shaw area property. CAPTION: Picture 1, Jeffrey Cohen in front of U Street building: "If I can do something good and help gring that area back . . . that's what I'm turned on about doing. Picture 2, Jeffrey Cohen's home in Cleveland Park is worth more than $512,000.