Inside the Manhunt for the Fox Lake Cop Killers

— -- The manhunt for the three suspects believed to be responsible for the death of a police officer in a suburb of Chicago continues and now investigators said they are relying heavily on the public for help.

One of the biggest areas of focus is the collection of video footage from around the scene of the shooting in Fox Lake, Illinois, on Tuesday morning.

Chief George Filenko, the commander of the Lake County Major Crime Task Force, said that investigators have not found any substantial leads on the videos they've viewed so far but they are working their way through video collected at local businesses as well as footage from private residential security footage.

For now, they are still working with the sole description of the suspects that was radioed in by Lt. Joe Gliniewicz before he was fatally shot: that he was pursuing two white men and one black man on foot.

Filenko said there are about 100 investigators working on this case now, and he has no deadline in mind until the alleged killers are caught.

"I'm not going to set a time limit on this," Filenko said. "[We] have a murdered colleague. We're not going to stop."

Last night capped an intense 14-hour manhunt immediately following the morning shooting, and they have since expanded their search zone as a result of the dearth of discoveries so far.

Local, state and federal officials were called to the neighborhood of Fox Lake, in the wake of the fatal shooting. The Lake County Sheriff's office said there were 400 law enforcement officers taking part in the manhunt on Tuesday, including both local and federal SWAT teams. Additionally, 48 canine units and six air support units were called in to cover the area, which initially only covered 2 square miles.

Just after 10 p.m. Tuesday that primary area was released by the sheriff's office and turned over to the Lake County Major Crimes Task Force, which is now handling the case.

"Obviously it's widened, it's widened from our original search area," Lake County Sheriff’s public information officer Christopher Covelli said this morning of the search area.

More than four area school districts closed today out of concerns about the active search.

"There is a sense of [worry] in the community, as there would be in any community in a situation like this. That's why we're out here," Covelli told ABC News.

Investigators are asking the public to be diligent in reporting anything that may mark suspicious activity.

"If they see something that's unusual and not normal to them, report it. Let us look into it," Covelli said.

Gliniewicz died after being shot following a foot pursuit of three men, police said. He described two of the men as being white and one as black, but gave no further description.

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