In a report shared with the family of Emmett Till, the Justice Department said that its investigation had not found enough evidence to support a new federal prosecution in the 14-year-old's murder.
While the department and the FBI called Till's murder "one of the most horrific examples of the violence routinely inflicted upon Black residents," in a letter to Till's family, they said that the new investigation did not uncover new facts that differed from those found in the previous investigation.
His family is expected to publicly respond to the report during a press conference Monday.
Till, 14, was killed in 1955 while visiting family in Mississippi after he was accused of whistling at and making sexual advances toward a white woman, Carolyn Bryant. He was kidnapped, badly beaten and found in the Tallahatchie River several days later.
Carolyn Bryant's husband, Roy Bryant, and his half-brother J.W. Milam were charged with Till's murder and acquitted by an all-white jury. The two men later confessed to the killing in a paid magazine interview months later.
Rev. Wheeler Parker, Till's cousin -- who was 16 at the time -- was in the house when Roy Bryant and Milam came looking for Till.
"I'm waiting to be shot, and I close my eyes," Parker recalled in an interview with ABC News for an upcoming documentary series "Let the World See." "I wasn't shot, I opened my eyes and they're passing by me. The guy said we're looking for fat boy, the fat boy from Chicago."
"They left with him, and that's the last time we saw him alive," he added.
Till's murder came at a time of intense racial unrest and animosity. When his mother, Mamie Till Mobley, demanded an open casket at his funeral, it helped spark the civil rights movement.
The Justice Department opened an investigation into Till's killing in 2004 but determined that there was no federal jurisdiction due to the statute of limitations. The investigation was originally closed in 2007 after a local grand jury declined to indict anyone on state charges.
It was reopened in 2018, following the publication of Timothy Tyson's book "The Blood of Emmett Till," in which Carolyn Bryant revealed she had not been telling the truth when she testified that Till had grabbed her and uttered obscenities.The Bryant family now deny that she had recanted her allegations.
This story is developing. Please check back for updates.