Last Updated Sep 3, 2015 6:52 AM EDT
FOX LAKE, Ill. -- Authorities broadened the hunt Wednesday for three suspects wanted in the fatal shooting of a popular Illinois police officer, acknowledging 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 of the 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 Tuesday. At least 100 investigators were on the ground.
Wednesday night, authorities responded to a report of two "suspicious subjects" running through a corn field in the Chicago suburb of Volo, about 5 miles from Fox Lake, Lake County Sheriff's Office spokesperson Detective Christopher Covelli told CBS Chicago.
Police officers with dogs conducted systematic searches with air support, although there was no evidence the report was related to the shooting suspects, Covelli said. Officers didn't spot anyone during the search, he said.
But he added, "Given the circumstances, we're taking it very seriously."
Later, Covelli issued a statement saying the report was a hoax by a local nanny seeking attention from the family she works for. Kristin B. Kiefer, 30, is being charged with two counts disorderly conduct - falsifying a police report.
Area schools will open Thursday, Covelli told CBS News. He said there would be a heavy police presence at the schools and along routes leading to them to make sure the community feels safe. Schools went on lockdown the day of the shooting and were closed Wednesday.
Residents of the usually sleepy community were urged to stay vigilant.
Lt. Charles Joseph Gliniewicz, a 30-year police veteran only a month from retirment, was shot Tuesday morning while pursuing the men he spotted on his way to work, said Lake County Major Crimes Task Force Cmdr. George Filenko, the lead investigator on the case. Gliniewicz told dispatchers the three ran into a swampy area, and he requested a second unit.
Dispatchers soon lost contact with him. Backup officers found him about 50 yards from his squad car with a gunshot wound. He died soon after.
Filenko said there was no indication he was intentionally targeted, though authorities did not rule out that possibility.
A major challenge facing authorities was the lack of a description of the suspects beyond the vague one that came from the officer, who told dispatchers he was pursuing three suspicious men - two white, one black - moments before he was shot.
"That was the only description provided," said Filenko. "So of course we're getting the public calling in every time they see that match of three individuals or even two individuals. We've closed out those leads completely as being unsubstantiated."
Asked by CBS News correspondent Anna Werner how dangerous the suspects are, Filenko replied, "They shot a police officer, so I think that speaks for itself -- extremely dangerous."
Hundreds gathered at a park Wednesday evening for a vigil in Gliniewicz's memory.
Fox Lake Mayor Donny Schmit said his death left a hole in his heart.
The officer's widow, Melanie Gliniewicz, took to the stage in a Fox Lake park surrounded by her four sons. She thanked the people attending the vigil and those offering their support and prayers.
Gliniewicz said her husband was her "best friend, my hero, the love of my life for the last 26 and half years."
A minister, Mike Johnson, said Gliniewicz died serving the community and was about helping others. He asked the crowd who among them would replace him.
Earlier, Schmit described Gliniewicz as a "dear friend."
"We lost a family member," Schmit said of the 52-year-old officer known around town as "G.I. Joe." ''His commitment to the people of this community has been unmatched and will be dearly missed."
Workers adorned the village hall with black and purple bunting in a display of mourning.
The initial, frenzied search for his killers involved law enforcement agencies from across the state. Some wore tactical gear and toted high-powered rifles. Officers took up positions on rooftops and along railroad tracks and scanned the terrain through rifle scopes and binoculars. Others leaned out of helicopters with weapons at the ready.
On Tuesday night, they declared the initial search zone clear, allowing investigators to begin poring over the crime scene and surrounding area.
Still, they knocked on doors with caution.
"I believe that the search teams did a thorough job, but I know there have been a number of national incidents where suspects have cleverly escaped or hidden in place," Filenko said. "So anything's possible."
Investigators were reviewing video recordings, but so far none has captured images of the suspects, Filenko said.
Despite the challenges, he told reporters that he felt the teams were making progress.
"As always, we're relying on the public, too," he said. "All it takes is one tip or good lead to break a case wide open."