Updated

The Latest on the renewed investigation into the killing of Emmett Till (all times local):

3:55 p.m.

A federal official says the renewed investigation of the killing of Emmett Till was prompted by a book published last year that includes a key figure's acknowledgement that she lied about the case.

A federal official familiar with the matter told The Associated Press that information published in the 2017 book led federal investigators to re-examine the case. The official wasn't authorized to discuss the matter publicly and spoke to AP on condition of anonymity.

The renewed investigation was first revealed in a recent federal report, which didn't specify what new information investigators were acting on.

The 2017 book "The Blood of Emmett Till" by Timothy B. Tyson quotes a white woman, Carolyn Donham, as saying during a 2008 interview that she wasn't truthful when she testified that Till grabbed her, whistled and made sexual advances at a Mississippi store in 1955.

— Associated Press writer Mike Balsamo contributed

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3:15 p.m.

The author of a book that included new revelations about the killing of Emmett Till says he shared all of his research materials with the FBI last year.

Timothy Tyson said at a news conference Thursday that he was contacted by the FBI several weeks after his book came out in January 2017. He says he assumes his book helped prompt the renewed investigation of the black teen's brutal slaying.

The Duke University scholar says he shared materials including recordings of 2008 interviews with a white woman, Carolyn Donham, acknowledging that she wasn't truthful when she testified that Till made sexual advances at a Mississippi store in 1955.

It was revealed this week that federal investigators have reopened its investigation of the crime that helped build momentum for the civil rights movement.

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12:30 p.m.

A potential witness in the slaying of black teenager Emmett Till says he's talked with law enforcement about the case in recent months.

Till's cousin, Wheeler Parker, said Thursday he's "pretty sure" an investigator asked him about what happened in a Mississippi store the day Till whistled at a white woman before his slaying in 1955.

Parker is 79 and the conversation occurred months ago, and he says he has a hard time remembering details. But Parker says the discussion likely occurred after the release of a book that raised questions about the Till case last year. The book says the woman acknowledged she wasn't truthful when she testified that the 14-year-old Till grabbed her.

Parker says the Justice Department hasn't told Till's family anything about the reopened investigation. He says they're waiting to get information just like everyone else.

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12:20 p.m.

A legal expert says it's unclear what new charges could result from a renewed investigation into the slaying of Emmett Till more than 60 years ago.

University of Mississippi law professor Tucker Carrington says conspiracy or murder charges could be filed if anyone still alive is shown to have been involved.

But he says too much time likely has passed to prosecute anyone for other crimes, such as lying to investigators or in court.

Two white men were previously tried on murder charges and acquitted by all-white juries, but they're both dead.

The Justice Department has told Congress it reopened an investigation of Till's slaying after receiving "new information." Authorities haven't said what that may be, but the move followed the release last year of a book about the case.

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11:30 a.m.

A Mississippi prosecutor isn't saying whether federal authorities have given him any new information since they reopened an investigation into the slaying of Emmett Till in 1955.

District Attorney Dewayne Richardson declined comment Thursday on any role he might have in the case. But he says it's always open until everyone involved has died.

Two white men were tried and acquitted by all-white juries after Till's brutal slaying 63 years ago. The 1955 trial was held in Tallahatchie County, which isn't in Richardson's district.

Richardson says it's not unusual for district attorneys to cooperate across district lines or for state and federal prosecutors to help local prosecutors. He says if a case were to move forward, he and the other district attorney could decide who would prosecute it.

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5 a.m.

The federal government has reopened its investigation into the slaying of Emmett Till, the black teenager whose brutal 1955 killing in Mississippi shocked the world.

A Justice Department report to Congress says the agency is reinvestigating Till's slaying after receiving what it calls "new information."

The report doesn't indicate what the new information might be. But it was issued in March following the publication last year of "The Blood of Emmett Till."

The book says a white woman acknowledged she wasn't truthful when she testified that the 14-year-old Till grabbed her and whistled at her in a store in 1955.

Two white men were acquitted in Till's lynching, but later confessed.