Atlanta:
That photo of the Rev. Dr. Martin Luther King, Jr. riding one of the first desegregated buses in Montgomery, Ala.? He took it. The well-known image of black sanitation workers carrying "I Am a Man" signs in Memphis? His. He was the only photojournalist to document the entire trial in the murder of Emmett Till, and he was there in Room 306 of the Lorraine Hotel, Dr. King's room, on the night he was assassinated.
But now an unsettling asterisk must be added to the legacy of Ernest C. Withers, one of the most celebrated photographers of the civil rights era: He was a paid F.B.I. informer.
On Sunday, The Commercial Appeal in Memphis published the results of a two-year investigation that showed Mr. Withers, who died in 2007 at age 85, had collaborated closely with two F.B.I. agents in the 1960s to keep tabs on the civil rights movement. It was an astonishing revelation about a former police officer nicknamed the Original Civil Rights Photographer, whose previous claim to fame had been the trust he engendered among high-ranking civil rights leaders, including Dr. King.
"It is an amazing betrayal," said Athan Theoharis, a historian at Marquette University who has written books about the F.B.I. "It really speaks to the degree that the F.B.I. was able to engage individuals within the civil rights movement. This man was so well trusted."
From at least 1968 to 1970, Mr. Withers, who was black, provided photographs, biographical information and scheduling details to two F.B.I. agents in the bureau's Memphis domestic surveillance program, Howell Lowe and William H. Lawrence, according to numerous reports summarizing their meetings. The reports were obtained by the newspaper under the Freedom of Information Act and posted on its Web site.
A clerical error appears to have allowed for Mr. Withers's identity to be divulged: In most cases in the reports, references to Mr. Withers and his informer number, ME 338-R, have been blacked out. But in several locations, the F.B.I. appears to have forgotten to hide them. The F.B.I. said Monday that it was not clear what had caused the lapse in privacy and was looking into the incident.
Civil rights leaders have responded to the revelation with a mixture of dismay, sadness and disbelief. "If this is true, then Ernie abused our friendship," said the Rev. James M. Lawson Jr., a retired minister who organized civil rights rallies throughout the South in the 1960s.
Others were more forgiving. "It's not surprising," said Andrew Young, a civil rights organizer who later became mayor of Atlanta. "We knew that everything we did was bugged, although we didn't suspect Withers individually."
Many details of Mr. Withers's relationship with the F.B.I. remain unknown. The bureau keeps files on all informers, but has declined repeated requests to release Mr. Withers's, which would presumably explain how much he was paid by the F.B.I., how he was recruited and how long he served as an informer.
At the time of his death, Mr. Withers had the largest catalog of any individual photographer covering the civil rights movement in the South, said Tony Decaneas, the owner of the Panopticon Gallery in Boston, the exclusive agent for Mr. Withers. His photographs have been collected in four books, and his family was planning to open a museum, named after him.
His work shows remarkable intimacy with and access to top civil rights leaders. Friends used to say he had a knack for being in the right place at the right time. But while he was growing close to top civil rights leaders, Mr. Withers was also meeting regularly with the F.B.I. agents, disclosing details about plans for marches and political beliefs of the leaders, even personal information like the leaders' car tag numbers.
David J. Garrow, a Pulitzer Prize-winning historian who has written biographies of Dr. King, said many civil rights workers gave confidential interviews to the F.B.I. and C.I.A., and were automatically classified as "informants." The difference, Mr. Garrow said, is the evidence that Mr. Withers was being paid.
Although Mr. Withers's motivation is not known, Mr. Garrow said informers were rarely motivated by the financial compensation, which "wasn't enough money to live on." But Marc Perrusquia, who wrote the article for The Commercial Appeal, noted that Mr. Withers had eight children and might have struggled to support them.
The children of Mr. Withers did not respond to requests for comment. But one daughter, Rosalind Withers, told local news organizations that she did not find the report conclusive.
"This is the first time I've heard of this in my life," Ms. Withers told The Commercial Appeal. "My father's not here to defend himself. That is a very, very strong, strong accusation."