Edgar Ray Killen was back in court Friday morning in Philadelphia after spending the night in the hospital.
The 80-year-old former Ku Klux Klansman was taken away from the courthouse in an ambulance with high blood pressure Thursday, the opening day of testimony.
He was not in the courtroom during the testimony of the trial's first witness, Rita Schwerner Bender, the widow of one of the three civil rights workers killed.
Michael Schwerner, James Chaney and Andrew Goodman were killed on a rural Neshoba County road after they had been in the county to investigate the burning of a black church. Their bodies were found 44 days later, buried in an earthen dam.
Prosecutors intend to prove that Killen planned the murders and helped round up Klansmen to chase down and kill the three.
Killen is in a wheelchair after breaking both legs in a March woodcutting