Les Whitten was a top legman to investigative reporter Jack Anderson. He was once tailed by the CIA and jailed by the FBI. (Family photo)

Les Whitten, an investigative reporter whose skill at cultivating government sources and securing secret documents — sometimes through threats or the use of a paid private investigator — made him a top legman of muckraker Jack Anderson and an enemy of President Richard M. Nixon, died Dec. 2 at an assisted-living community in Adelphi, Md. He was 89.

He had recently been hospitalized for sepsis, said a son, Les Whitten III.

A self-described “swashbuckler,” Mr. Whitten was an aspiring novelist who covered wars in the Dominican Republic and Vietnam before joining the staff of the country’s most popular daily news column, the Washington Merry-Go-Round, in 1969.

Helmed by Anderson, a reporter whose investigative prowess was matched by a reputation as an unrepentant, self-aggrandizing showman, the syndicated column reached tens of millions of readers. It broke news on topics as diverse as a CIA plot to assassinate Cuban revolutionary Fidel Castro and the Nixon administration’s secret foreign policy shift toward Pakistan and away from India, which earned Anderson a Pulitzer Prize for national reporting in 1972.

Mr. Whitten was “the best reporter in the country,” Anderson told The Washington Post in 1978, and he had a hand in nearly all the column’s stories for a decade until he left to write thrillers and focus on his translations of the French poet Charles Baudelaire.

Still, Mr. Whitten and other reporters for Anderson — including a young Brit Hume, who later became a Fox News anchorman, and Jon Lee Anderson, now a staff writer for the New Yorker — were only occasionally credited with a byline.

Working largely behind the scenes, they practiced an aggressive, occasionally unscrupulous brand of reporting that included the use of bribes and blackmail, according to Mark Feldstein, author of “Poisoning the Press: Richard Nixon, Jack Anderson and the Rise of Washington’s Scandal Culture.”

During the Watergate investigations, Mr. Whitten “was trying to get some leaks and couldn’t get it,” Feldstein said in a phone interview. “He threatened his source by saying, ‘If you don’t give this to me I’ll say it came from you, but if you give it to me, we’ll have lunch and I’ll say it came from ‘a source near the White House.’

“You can decry it from the standpoint of traditional journalistic ethics, but on the other hand, it allowed him to pry out information the public otherwise wouldn’t learn about.”

As Anderson’s chief deputy — or “senior ferret,” as New York Times journalist Tom Buckley once dubbed him — Mr. Whitten was handed assignments that included spying on the private lives of FBI Director J. Edgar Hoover and his top aide, Clyde Tolson. Another reporter was assigned to dig through Hoover’s trash.

Just as often, however, Mr. Whitten and Anderson were on the receiving end of spying efforts, targeted by the Nixon administration for their critical coverage of the White House and leaks of government documents. The duo were trailed by the CIA, and at one point, Nixon associates G. Gordon Liddy and E. Howard Hunt plotted to assassinate Anderson using LSD or what Liddy later described as “Aspirin Roulette.”

The idea of placing poisoned aspirin in the Anderson family’s medicine cabinet was rejected, Liddy wrote in a memoir, because “it would gratuitously endanger innocent members of his family and might take months before it worked.” He and Hunt were soon assigned to bug the Democratic National Committee headquarters in the Watergate hotel and office complex.

Mr. Whitten was nearly the subject of a major First Amendment case in 1973, when he was arrested by a squad of FBI agents in downtown Washington as he helped a source load boxes of stolen government documents into his car.

He said he had been trying to help the source return the documents, which had been taken from the Bureau of Indian Affairs by Native American activists the previous year and had provided grist for columns about government mistreatment of Indian tribes.

Tagged with the precedent-breaking charge of possessing the stolen documents — previously, journalists had been considered immune from legal action if they simply received, unsolicited, a cache of secret files — Mr. Whitten faced a possible 10 years in prison and soon became a cause celebre in Washington, where reporters donned “Free Les Whitten” buttons and The Post’s Herblock drew him into a political cartoon.

A grand jury dropped the charges, finding them without merit. By then, however, Anderson had already prepared an unusual defense strategy for his colleague. In an attempt to undercut the government and show that prosecuting Mr. Whitten for receiving secret documents was “selective and arbitrary,” as Feldstein later put it, he arranged a meeting with Interior Secretary Rogers Morton.

“You’ve done more for the Indians than any Interior secretary in history,” Anderson said, according to “Poisoning the Press.” “If you could slip me some confidential memos on what you’ve done, I could write a credible story.”

The sweet talk worked, and Anderson soon had a batch of secret files as classified as the ones handled by Mr. Whitten.

“If this ever comes to trial,” Mr. Whitten recalled Anderson saying, “we’re going to have a heck of a witness for your defense.”

Leslie Hunter Whitten Jr. was born in Jacksonville, Fla., on Feb. 21, 1928, and grew up in Washington, graduating from Woodrow Wilson High School in the District.

At the urging of his father, an electrical engineer and executive with the manufacturer Graybar, Mr. Whitten studied civil engineering at Lehigh University in Bethlehem, Pa. But the field proved a poor fit — “from the time I was 18, I wanted to be a poet,” Mr. Whitten later said.

Mr. Whitten seemed a changed man upon his return from Army service, his son Les Whitten III said, switching his majors to English and journalism and becoming editor of the school newspaper. He graduated in 1950 and, after attempts to become a novelist and poet (he moved to Paris and befriended a toga-wearing Raymond Duncan), he joined the Munich office of Radio Free Europe in 1952.

After stints with The Post and Hearst newspapers, he joined the Washington Merry-Go-Round following the death of Anderson’s business partner and the column’s founder, Drew Pearson.

The former Phyllis Webber, his wife of 65 years, died in January. Survivors include a daughter from a relationship, Deborah Engle of Laguna Beach, Calif.; three sons from his marriage, Les Whitten III of Catonsville, Md., Dan Whitten of Bethesda, Md., and Andrew Whitten of Scottsdale, Ariz.; and six grandchildren.

Mr. Whitten wrote nearly a dozen novels in all, including his 1965 debut “Progeny of the Adder,” about a vampire who dumps his victims in the Potomac River, and his 1967 follow-up “Moon of the Wolf,” about a werewolf in small-town Mississippi. The book was adapted into a 1972 ABC Movie of the Week starring David Janssen.

The success of a 1976 political novel, “Conflict of Interest,” which featured an alcoholic speaker of the House and a few salacious bedroom scenes, led him to step away from his job at the Merry-Go-Round. He continued to contribute to the column part-time for several years.

“Before, I was strung like a harp every day,” he told The Post in 1978, soon after entering semiretirement. “I’d have four or five stories going; I didn’t know if some FBI guy or grand jury was going to call, or if some mob guy would do a breath job on the phone. If we were working on a mob story, I’d start my car by reaching my arm in, so I’d only miss an arm if it blew up. It wasn’t what you’d call your little old backyard swing by the Swanee River.”

Correction: An earlier version of this obituary incorrectly described the site of the 1972 break-in at Democratic National Committee headquarters. The DNC offices were at the Watergate hotel and office complex, but they were not located inside the hotel itself. The story has been updated.