A 2017 book that revealed lies by a key figure in the Emmett Till case has prompted the U.S government to renew its investigation into the brutal 1955 slaying, a federal official said Thursday.

The reopening of the case had stayed quiet until the contents of a federal report came to light earlier in the day. Till relatives and social justice activists welcomed a fresh look at the killing that shocked the country and stoked the civil rights movement, but acknowledged that the passage of time could hamper justice.