Mrs. Bradley traveled to Mississippi to testify at the trial, staying in the home of Dr. T.R.M. Howard in the all-black town of Mound Bayou. Others staying in Howard's home were black reporters, such as Cloyte Murdock of Ebony magazine, key witnesses, and Congressman Charles Diggs of Michigan, later the first chairman of the Congressional Black Caucus. Howard was a major civil rights leader and fraternal organization official in Mississippi, the head of the Regional Council of Negro Leadership (RCNL), and one of the wealthiest blacks in the state.
The day before the trial, Frank Young, a black farm worker, came to Howard's home, stating that he had information indicating that Milam and Bryant had help in their crime. Young's allegations sparked an investigation that led to unprecedented cooperation between local law enforcement, the NAACP, the RCNL, black journalists, and local reporters. The trial began on September 19, 1955, 22 days after the murder. Moses "Mose" Wright, Emmett's great-uncle, was one of the main witnesses called up to testify by lead prosecutor Gerald Chatham. Pointing to one of the suspected killers, he identified the man who had killed his nephew.
Another key witness for the prosecution was Willie Reed, an 18-year-old high school student who lived on a plantation near Drew, Mississippi in Sunflower County. The prosecution had located him, thanks to the investigation sparked by Young's information. Reed testified that he had seen a pickup truck outside an equipment shed, on a plantation near Drew managed by Leslie Milam, a brother of J.W. Milam and Roy Bryant. He said that four whites, including J.W. Milam, were in the cab and three blacks were in the back, one of them Till. When the truck pulled into the shed, he heard human cries that sounded like a beating was under way. He did not identify the other blacks on the truck.
On September 23 the all-male, all-white jury acquitted both defendants. Deliberations took merely 67 minutes; one juror said, "If we hadn't stopped to drink pop, it wouldn't have taken us too long."The hasty acquittal outraged people throughout the United States and Europe and energized the nascent Civil Rights Movement.