Alan R. Novak, a businessman who helped develop the District’s Mandarin Oriental hotel, was a partner in an investment group that purchased the city’s landmark Ritz-Carlton Hotel and was an early proponent of investing in blighted neighborhoods east of the Anacostia River, died May 23 at his home in Washington. He was 83.

A spokeswoman for the D.C. medical examiner’s office said a determination of the cause is pending further tests.

In a career spanning six decades, Mr. Novak traversed white-collar law, executive-branch consulting, venture capitalism and art collecting. The son of Jewish immigrants from Eastern Europe, he attended Yale and Oxford universities on scholarships, was a Supreme Court clerk, worked on a Lyndon B. Johnson administration communications task force and consulted for the Carter White House during the 1980 presidential campaign.

On the cusp of leaving office in 1981, Carter appointed Mr. Novak to the Commission of Fine Arts, a D.C. watchdog panel on the city’s aesthetics. He was involved in intense negotiations over the selection of Maya Lin’s black granite design for the proposed Vietnam Veterans Memorial on the Mall.

During his four years on the commission, Mr. Novak also advocated construction of the gargantuan Washington Harbour condominiums and office complex on the Georgetown waterfront. It was not to everyone’s taste — commission chair J. Carter Brown denounced it as “Xanadu on the Potomac” — but it became a gateway to the creation of the popular Georgetown Waterfront Park.

“At the time, there was nothing on the Georgetown waterfront but debris,” Mr. Novak later told the Washington Business Journal. On the waterfront’s last undeveloped parcel, Mr. Novak in the 2000s developed HarbourSide, a $150-million, mixed-use glass structure that included a new Swedish embassy building.

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Starting in the 1970s, Mr. Novak was involved in venture investment groups with interests ranging from telecommunications to oil. He acquired an interest in the Washington, New York and Houston branches of the upscale Ritz-Carlton hotel chain and also bought property in Aspen, Colo., to develop a Ritz-Carlton in that ski-resort epicenter.

With partners, he helped build the Mandarin Oriental, which opened in 2004 on a long-vacant site next to the 14th Street Bridge on the Southwest D.C. waterfront.

“We were at a ribbon-cutting at the Mandarin, and we told Tony Williams that we’d been lucky here in the city and we’d like to give back — what would he recommend?” Mr. Novak told the Business Journal in 2011, referring to the mayor at the time, Anthony Williams. The mayor replied, “Go east of the river.”

That became a chief mandate of Mr. Novak’s real estate development firm CityInterests. The company’s projects ranged from luxury apartments in the District’s Shaw neighborhood to the purchase of Robinson Terminal North, a former Washington Post Co.-owned warehouse in Alexandria, Va., as a possible hotel site amid the city’s waterfront redevelopment.

In recent years, CityInterests has focused on properties in the District’s poorest neighborhoods east of the Anacostia River. In 2004, the company spent $11.1 million at auction to buy a 26-acre mostly vacant plot called Parkside with the intention of constructing mixed-use, mixed-income apartments and town homes near the Minnesota Avenue Metro station.

At the heart of the investment, Mr. Novak said, was helping residents with limited access to solid schools and educational and professional opportunities. Through federal grants and other initiatives, he worked to secure an early-childhood education center, a health clinic, green spaces and improvements in infrastructure for Parkside.

Mr. Novak described the experience at Parkside as idealism tempered by reality. An effort to lure a quality sit-down restaurant, Ray’s the Steaks at East River, shuttered soon after opening in 2010 at a shopping center owned by CityInterests. He said he had to keep hoping that, in the face of setbacks, public and private investment would come eventually.

“The effects of slavery and discrimination don’t go away because you pass a law,” he told the Washington Business Journal. “You have to have the things that make a neighborhood function before you think about bricks and mortar — education, health care amenities, food, parks and recreation, infrastructure, transit. Who takes that first step? Who takes the second?”

“I’m not Santa Claus,” he added. “But there are others who think we’re rapacious developers, and that’s not true either. If I wanted to be rapacious, I’d stay in Georgetown.”

Alan Richard Novak was born in Manhattan on June 2, 1934, and grew up in Queens. His father was a textile buyer, and his mother was an accountant.

On a Navy scholarship, he received a bachelor’s degree in economics from Yale University in 1955. After three years in the Marine Corps, he received a Marshall scholarship that enabled him to study at the University of Oxford in England. He graduated in 1963 from Yale Law School, ranked third in his class.

He was an editor of the Yale Law Journal, where his satirical piece about Connecticut’s strict legal prohibition of oral contraceptives, “Man, His Dog and Birth Control: A Study in Comparative Rights,” was reprinted in the volume “Juris-Jocular: An Anthology of Modern American Legal Humor.”

After clerking for Supreme Court Justice Potter Stewart, Mr. Novak worked for the law firm of Cravath, Swain & Moore in New York and entered government service in 1965 as a legislative aide to Sen. Edward M. Kennedy (D-Mass.). He later served as a member of a Johnson White House task force on communications policy and as personal assistant to undersecretary for political affairs Eugene V. Rostow.

In the 1970s, Mr. Novak began investing in art through a partnership that bought dozens of 19th-century paintings, many of them exemplars of the American Luminist school of landscape works. Mr. Novak was advised by his sister, Barbara Novak, a noted art historian.

Mr. Novak was an Arena Stage trustee and an executive committee member of the influential Federal City Council civic group.

Survivors include his wife of 58 years, Kath Wijkstrom “Kate” Novak of Washington; twin sons, Adam Novak of Los Angeles and Jonathan Novak of Washington; his sister; and three grandchildren.