Alfred E. Lewis, 81, a reporter for The Washington Post for 50 years whose indefatigable coverage of the police beat through decades of historic change made him a newsroom mainstay and a walking repository of District lore and legend, died yesterday at Washington Adventist Hospital. He had cancer. Between his 1935 arrival and 1985 retirement, Lewis, known affectionately as "Uncle Al," turned in 15,000 bylined stories, many of them Page 1 exclusives. He scooped his competitors and cultivated and protected legions of police sources. He also tutored generations of young reporters who joined the paper. In addition to covering everyday police and crime stories, Lewis wrote about some of the more notable events in history. He covered the bloody 1950 attempt on the life of President Truman. Alone among reporters, he was admitted to the Democratic National Committee headquarters in the Watergate on the day of the 1972 break-in there. The first account printed in The Post on what was to become one of the major stories of the century carried his byline.

Taken together over the years, Lewis's stories and exploits form a panorama of social, political and economic change, some of which his work helped to bring about. A 1945 series on escapes from the old D.C. Jail prompted numerous changes, including creation of a separate Corrections Department. New policies or investigations followed stories about arrest and arraignment procedures, ticket-fixing, the activities of a police chief and a series on a gambling figure. Crime, criminals and the way they were publicly portrayed changed during his reporting career. When he began, many of those on the wrong side of the law were still regarded with wry disapproval as mere scoundrels or rascals; he watched social pathology decay into an age of heavy firepower, widespread drug use and urban despair.

One of the biggest stories Lewis helped break came in June 1972. D.C. police had been called to the Democratic National Committee headquarters in the Watergate complex, where a break-in had occurred. Lewis, a familiar and trusted figure to top police officials, went into the building with investigators and remained there unchallenged through the day, gathering information available to no other news outlet.

In their book "All the President's Men," Carl Bernstein and Bob Woodward memorably described Lewis as "something of a legend in Washington journalism -- half cop, half reporter, a man who often dressed in a blue regulation Metropolitan Police sweater buttoned at the bottom over a Star-of-David buckle." They went on: "Lewis had never really 'written' a story; he phoned the details in to a rewrite man, and for years The Washington Post did not even have a typewriter at police headquarters." Reached after Lewis's death, Woodward, now a Post assistant managing editor, said Lewis was able to get the kind of details concerning the burglary and the burglars that convinced Post reporters and editors that this was no minor crime. "His work laid the foundation for what the paper was able to do in reporting the story," Woodward said. Lewis's aggressive newsgathering techniques and his sometimes idiosyncratic personal habits reminded many colleagues of the raffish and swaggering "Front Page" era of journalism. Alfred E. Lewis was born in Philadelphia, the son of a tailor. When he was a boy, the family moved to Waterbury, Conn. He attended the City College of New York and received a law degree at Southeastern University here. He began his journalism career with the old New York Evening Graphic, where he ran errands for staff members Ed Sullivan and Walter Winchell. His next stop was with United Press. A day off in 1935 took him to Washington and The Post. After two weeks as a copy boy, he was on his way to police headquarters, where he soon covered his first homicide. That was 59 years ago, a time when relatively few of the city's killings involved guns. "People used knives, baseball bats, frying pans," Lewis said. "Anything they could get their hands on." In his first homicide, it was an ax. Lewis recalled arriving at the scene and asking an officer where the body was. "Kid," he was told, "you're stepping in some of it." In competing for a scoop, Lewis was relentless, but he was not a cutthroat. One of the lessons he taught newcomers, former executive editor Benjamin C. Bradlee recalled, was that "being a nice guy never interfered with the job." Lewis cultivated police officers who might someday supply him with information. "Nothing ever happened in the police department of any consequence, including the births of children to policemen," that he did not know about, said Ben W. Gilbert, a retired deputy managing editor, who was city editor in the 1940s and '50s. Lewis attended weddings, funerals and wakes, and showed what police officers took to be a genuine concern for their welfare. A major story from his early years came when a robbery squad lieutenant called him to Seventh and M streets NW. "Notice anything?" the lieutenant asked. Lewis looked around at empty sidewalks. "Where is everybody?" he demanded. Everybody was staying home because a madman had been terrorizing the area for three weeks, stalking people on the streets and shooting them, apparently at random. Seven people had been killed and more wounded, but the newspapers had carried nothing because the victims were black. "The Post ran the story and the other four papers had to catch up," Lewis said. "That sure did change things." Lewis liked to remain on good terms with those he covered, but there was little he could do in the late 1940s about his encounters with Police Chief Robert W. Barrett. The Post in those days, according to Bradlee, "was driving Barrett crazy with expose's" about various police problems, and Barrett was venting his wrath on Lewis. Instructed regularly by Gilbert to confront the chief and ask for his explanations, Lewis displayed, according to Bradlee, a look of wrenching anguish. But, Bradlee recalled, Lewis would go in, time after time, and would as regularly emerge, abused and dejected, but with the story he went in for. Thereby, Bradlee said, he taught a generation of colleagues such bedrock principles of journalism as: Work harder than the other guy, and never mind the obstacles. When World War II broke out, Lewis took leave from The Post to join the Marine Corps, serving as a combat correspondent for 3 1/2 years, winning a commendation for serving on Bougainville under Japanese fire for 21 consecutive days in 1944. On returning from the Pacific, he was soon back at the police beat. "I always wanted to be a police reporter," he said. "Nothing else." His renown grew over the years, expanding to include the white socks he habitually wore, the hot water he drank with his lunchtime sandwich, and his longevity. At the time he retired, he had possibly held his job longer than any reporter then working in Washington. In the early 1960s, he accompanied a delegation of police officials to the White House and President Kennedy singled him out for a question. What did the "E." in Alfred E. Lewis stand for? (It stood for Edward.) Others might have been asked to type their own stories, Gilbert said, but Lewis was never asked to change "He was such a damn good reporter," Gilbert explained. One of his thousands of bylines appeared on a book: "Surprise! Surprise!" which he coauthored with Post staff members Kevin Klose and Ron Shaffer, about a prototypical police sting operation. In a special version of The Post prepared for a celebration of Lewis's 50th anniversary at the paper, Publisher Donald E. Graham placed him in "the great tradition of those who performed brilliantly through all the decades of the modern Post." "When they recite the names of the great people who built this place, Uncle Al's belongs right up there," Graham said. Survivors include his wife, Gladys, of Silver Spring; two daughters, Eileen Lewis of Springfield, Mo., and Shirley Lewis Abel of Silver Spring; and a grandson.