The Justice Department announced on Monday that it had closed an investigation into the abduction and murder of Emmett Till, the African American teenager whose gruesome killing by two white men more than six decades ago in Mississippi helped begin the civil rights movement.

In a news release dated Dec. 6, federal officials said there was not enough evidence to pursue charges in the case, which was reopened after a historian claimed in a book that Carolyn Bryant Donham, the central witness whose account of an encounter with Emmett led to his death, had recanted the most salacious portions of her story — that he had grabbed her and made sexually suggestive remarks.

Citing the statute of limitations and Ms. Donham’s denial that she had ever changed her story, the Justice Department said it could not move forward with prosecuting her for perjury.

During a moment of the trial in which jurors were not present, Ms. Donham claimed that the teenager had made sexually vulgar comments toward her and physical contact. But in a book published in 2017, “The Blood of Emmett Till” by Timothy B. Tyson, the author wrote that Ms. Donham had recanted her testimony in a 2008 interview, saying that the earlier stories she told were “not true.”

“Nothing that boy did could ever justify what happened to him,” Mr. Tyson, a researcher and historian at Duke University, quoted Ms. Donham as saying in the book.

Mr. Tyson’s claim generated outrage and renewed calls for the case to be reopened. Kristen Clarke, who leads the Justice Department’s civil rights division, delivered the news to the family in person that the case was formally closed.

In a statement on Monday, the Justice Department said Mr. Tyson, despite saying he had recorded two interviews with Ms. Donham, provided just one recording to the F.B.I. that did not contain a recantation.