Frank Patrick Muto, 71, the Senate Democratic photographer for 18 years before his retirement in 1975, who had covered World War II as a news photographer and then directed the still pictures branch at the old War Department, died of congestive heart failure Wednesday at Sunrise Hospital in Las Vegas, Nev.

Mr. Muto, who was born in Princeton, N.J., began working as an office boy for the New York Daily News at the age of 15. He then worked as a photographer and photo editor for several years.

In the 1930s, he worked as a picture editor for screen magazines on the West Coast and as director of tourist photography for the Italian government before joining the old International News Service as a war correspondent. He covered the Polish and Norwegian campaigns and the Finn-Russian war and was subsequently captured by the Russians, Romanians and Germans before returning to the United States.

A former Army major, Mr. Muto served as a public relations and still-photograph officer, beginning the still-picture public relations section for the old War Department, now the Army Pictorial Service, as an Army captain during World War II.

During that time, until the end of the war, he also went on special assignments to all theaters of operation and photographed the official surrender of Japan.

Mr. Muto then worked as a free-lance photographer before becoming Senate Democratic photographer in 1957. He retired in 1975.

A former resident of Falls Church, he and his wife, Anne T. Muto, moved to Las Vegas last year.

Mr. Muto received medals from Poland and Finland for humanitarian service to their countries during World War II.

He was a member of the White House News Photographers Association.

Besides his wife, survivors include a brother, Alfonso, of Bailey's Crossroads, and a sister, Margaret DiAnnunzio of River Vale, N.J.