In September 1955, the Michigan Representative garnered national attention when he attended the trial of the two white Mississippians accused of murdering Emmett Till.

Diggs resigned from the United States House of Representatives and served 14 months of a three-year sentence for mail fraud, although he maintained his innocence.

[citation needed] He was rooted in his family's business, the House of Diggs, which at one time was said to be Michigan's largest funeral home.

[4] In 1954, Diggs defeated incumbent U.S. Representative George D. O'Brien in the Democratic Party primary elections for Michigan's 13th congressional district.

[citation needed] The first African American to be elected to Congress in Michigan, Diggs made significant contributions to the struggle for civil rights.

In April 1955, three months after he was first sworn in to Congress, he gave a well-received speech to a crowd of about 10,000 in Mound Bayou, Mississippi, at the annual conference of the Regional Council of Negro Leadership (RCNL), probably the largest civil rights group in the state.

[5] Later that same year, Diggs returned to Mississippi, where he received national attention as the only congressman to attend and monitor the trial of the accused killers of Emmett Till, a black teenager from Chicago who was murdered during a trip to the state.

[5] Soon after the trial concluded, white mobs began to search for the witnesses involved in the case, including then-18-year-old Willie Reed.