The photographs stunned the country: A 14-year-old boy dead in a coffin, his head crushed, an eye gouged, his body disfigured beyond recognition from an agony in which he was beaten, shot, tied with barbed wire to a weight and submerged in the Tallahatchie River of Mississippi.

The young man was Emmett Till. His murder in 1955 – punishment for the transgression of whistling at or otherwise offending a white woman – became the most infamous of the thousands of lynchings visited upon African-Americans in the Jim Crow South. Till’s death galvanized the civil rights movement, but only after Simeon Booker helped deliver the story to a national audience.

Booker, the Washington, D.C., bureau chief of Jet and Ebony magazines for five decades, died Dec. 10 at an assisted-living community in Solomons, Maryland. He was 99 and had recently been hospitalized for pneumonia, said his wife, Carol Booker.

Few reporters risked more to chronicle the civil rights movement than Booker. He was the first full-time black reporter for The Washington Post, serving on the staff for two years before joining the Johnson Publishing Co. to write for Jet, a weekly, and Ebony, a monthly modeled on Life magazine, in 1954.

From home bases in Chicago and later in Washington, Booker ventured into the South and sent back dispatches that reached black readers across the United States. He was in Chicago, Till’s hometown, when he heard that the young man had disappeared in Money, Mississippi.

Booker instinctively went to the home of the young man’s mother, Mamie Till-Mobley, and earned her trust as she moved through her terror and then grief. He was with her at the funeral home where, over the objections of others, she insisted that the casket bearing her son’s mutilated corpse be opened. Booker described the scene in Jet:

“Her face wet with tears, she leaned over the body, just removed from a rubber bag in a Chicago funeral home, and cried out, ‘Darling, you have not died in vain. Your life has been sacrificed for something.'”

No mainstream news outlets published the images of Till’s body, but their appearance in Jet and other African-American publications helped make the Till murder “the first great media event of the civil rights movement,” historian David Halberstam wrote in his book “The Fifties.”

As one of the few black reporters in Washington, Booker wrote a column for Jet called Ticker Tape U.S.A. and led editorial coverage of the executive and legislative branches at a time when black reporters were largely excluded from news events as from everyday life. He wrote that he was “never prouder of Jet’s role in any story” than in 1961, when he helped cover a Freedom Ride from Washington to New Orleans.

A mob firebombed one of the buses in Anniston, Alabama. Thugs forced their way aboard Booker’s coach and beat the protesters. In Birmingham, Alabama, Ku Klux Klansmen waited to beat them again.

With help from U.S. Attorney General Robert Kennedy, Booker and the Freedom Riders were eventually flown to safety. But such demonstrations continued, and integration was enforced in interstate travel.

Simeon Saunders Booker Jr. was born Aug. 27, 1918, in Baltimore, where his father, a Baptist minister, was the director of a YMCA for blacks.

“From an early age, I knew I wanted to be a writer,” Mr. Booker told the Vindicator, a Youngstown newspaper. “Teaching and preaching were the best advances for blacks at the time. But I wanted to write.”

He received an English degree in 1942 from Virginia Union University, then began his career at the Baltimore Afro-American. He later joined the Cleveland Call and Post, also an African-American publication, where he won a Newspaper Guild Award for a series covering slum housing – and where he was fired for trying to unionize the staff.

In 1950, he received a prestigious Nieman Foundation fellowship at Harvard University.

After the Nieman, Booker wrote to numerous newspapers seeking employment. “The only one to answer me,” he told The Post years later, “was Phil Graham of The Washington Post.”