Brian Readus, 45, killed in motorcycle crash on Interstate 55 near Bolingbrook, Illinois

Readus was alone on a motorcycle and directly behind a Dodge Durango carrying a driver and a passenger, Wilkes said. An investigation concluded that "for unknown reasons, (Readus) crashed into the rear of the SUV," Wilkes said. 

No one in the SUV was injured. The crash remains under investigation, Wilkes said.