NEW YORK —The woman at the center of the trial of Emmett Till’s alleged killers has acknowledged that she falsely testified he made physical and verbal threats, according to a new book.

Historian Timothy B. Tyson said Saturday that Carolyn Donham broke her long public silence in an interview with him in 2008. His book, “The Blood of Emmett Till,” comes out this week.

“She told me that ‘Nothing that boy did could ever justify what happened to him,'” said Tyson, a Duke University research scholar.

Emmett Till was a 14-year-old black tortured and killed in 1955 in Mississippi after allegedly whistling at a white woman, then known as Carolyn Bryant.

His murder became national news and was a galvanizing event in the civil rights movement. During the trial, Bryant said that he had grabbed her, and, in profane terms, bragged about his history with white woman. The jury was not present when she testified.

Donham’s then-husband, Roy Bryant, and his half brother, J.W. Milam, were acquitted by the all-white jury. Both men, who later told Look magazine they did kill Till, have since died. The Justice Department re-examined the case a decade ago, but no one was indicted as a killer or an accomplice.

Tyson said that he spoke with Donham after her daughter-in-law, Marsha Bryant, contacted him after reading “Blood Done Sign My Name,” his book about a racist murder during his childhood in Oxford, North Carolina, and invited Tyson to meet with her and Donham.

Tyson said he and Donham had two conversations.

Carolyn Donham’s whereabouts have long been a mystery, but North Carolina voter rolls list a Carolyn Holloway Donham in Raleigh. Holloway is her maiden name.