Illinois State Police identified the bicyclist killed in Granite City last week as Richard K. Thomas, 54, of Granite City.
Illinois State Police Trooper Calvin Dye said a "person of interest" has been identified in the case. He declined further comment.
Thomas was hit by a car just before 11 p.m. Aug. 28. He was riding west on East Chain of Rocks Road near Warson Road.
The car was driving behind the bicyclist when the front passenger side of the vehicle struck the bicyclist, Dye said. The driver left the scene.
Thomas was not wearing reflective clothing and the bike was not illuminated, according to police.
A passerby called for medical assistance, and Thomas was taken to a St. Louis hospital where he later died.
Funeral arrangements for Thomas are being handled by Wojstrom Funeral Home in Granite City. A visitation will be held from 11 a.m. to 1 p.m. Saturday at the funeral home with a funeral service following at 1 p.m.
He is survived by two sisters and a brother.