The alleged assault occurred about 9 p.m. Saturday in the 0-100-block of East 121st Place.
A train struck and killed Theus Beal, 32, at approximately 9:30 p.m. near the train station at 87th Street.
After the accident, power was shut off on the Red Line between 79th and 95th streets.
Shuttle buses operated between those stations until rail service was restored Sunday morning.
The Sun-Times Media Wire contributed to this report.