FOX LAKE, Ill. — Authorities broadened the hunt Wednesday for three suspects wanted in the fatal shooting of a popular Illinois police officer, even as they acknowledged that they had no indication the men were still in the area where the slaying happened.

After an intensive 14-hour “grid search” of homes, railroad tracks and marshland in the village of Fox Lake, the second-day manhunt turned to the painstaking detective work of chasing down tips, collecting and reviewing surveillance video and interviewing residents near the crime scene. Meanwhile, new search teams rippled out into subdivisions beyond the initial 2-square-mile perimeter established on Tuesday.