The long, slow march of prosecuting unpunished killings from the civil rights era continues Tuesday when James Seale goes on trial.

The 71-year-old former crop-duster faces federal kidnapping and conspiracy charges in connection with the abduction and slayings of Henry Dee and Charles Moore, two African-American teenagers, in May 1964.

Dee and Moore, both 19 years old, were abducted, beaten, tied up, weighted down and tossed into the Mississippi River, where they drowned, according to a copy of the FBI case file that has been made public. If convicted, Seale could be sentenced to life in prison.

Seale's trial marks the sixth civil rights-era case that has been prosecuted in Mississippi since 1990, when a grand jury here indicted Byron De La Beckwith for the 1963 assassination of Medgar Evers, the field secretary for the Mississippi NAACP.

A cascade of prosecutions followed the Beckwith conviction. The tally so far: Authorities in seven states have re-examined 29 killings from the civil rights era and made 29 arrests, leading to 22 convictions.