UPDATED: 11:09 p.m.
CHICAGO (CBS) -- Police resumed their search for three suspects in the killing a Fox Lake police lieutenant known to many in the community as "G.I. Joe.," but the investigation continues.
Late Wednesday evening, police have set up a perimeter in Volo, Ill. along Route 12 after receiving a report of several people darting through a field. Volo is about five miles from Fox Lake. K9 unites and a police helicopter have been called in. There was also a large police presence near Lakemoor Golf Club.
Earlier Wednesday, George Filenko, commander of the Lake County Major Crimes Task Force, said investigators were continuing to gather evidence and follow leads. He said the suspects could be out of town, or even out of the state. Filenko would not say if there were any witnesses, but that investigators have some surveillance tape. The quality of that tape was described as "not great."
Lake County Sheriff's Det. Chris Covelli said police officers had been searching the area after Fox Lake Police Lt. Charles Joseph Gliniewicz was shot and killed while on a foot chase Tuesday morning. Sources said he was shot twice, once in his vest.
The Lake County Major Crimes Task Force says they're identified several people they want to talk to and federal authorities are using advanced equipment to screen surveillance video.
The shooting happened in a secluded area, which is surrounded by a subdivision, Filenko said.
Every home in a two-mile area around the crime scene was search and cleared.
Investigators have not released any descriptions of the suspects, only that they are two white males and a black man. Filenko said the investigation is continuing, with detectives gathering evidence and following up on leads, which includes more than 100 tips. The U.S. Marshal, FBI and ATF are also assisting local authorities.
At a news midday news conference, Filenko said that some surveillance tape had been collected and investigators were seeking more, but he didn't know if there was a dash camera in the officer's car. He also said investigators believe the suspects left the crime scene on foot.
Jimmy Vicicondi works at Precision Chrome, not far from where Gliniewicz's was killed. The plant's cameras caught nothing, but Vicicondi did see Gliniewicz's squad car parked, and abandoned.
"He was actually parked at the entrance to the old concrete plant," Vicicondi. "It seemed like he was going to go into the plant."
Covelli said more than 400 police officers, 48 K-9 units, police boats, and helicopters equipped with heat-seeking infrared equipment searched a grid around the area where Gliniewicz was slain, but did not find the three men the lieutenant had been chasing. Late Tuesday night, after 14 hours of searching, the Lake County Sheriff's office determined the suspects were no longer in the search perimeter.
"We had over 400 police officers out here yesterday. We had over 45 canine units and numerous aircraft," he said.
Police have begun "saturation patrols" in the Fox Lake area to help residents feel safe with the suspects still at large.
Social media investigators have been brought in to work on the case, reports CBS 2's Marissa Bailey.
George Filenko, head of the Lake County Major Crimes Task Force, says the social media investigators are part of a multiple pronged approach to find the suspect. He says they've received hundreds of tips on social media.
Facebook, Twitter and message boards are all places where investigators will look to try and find anything they can to lead them to the suspects.
Many criminals will brag or at least start talking about the crimes they committed. It's that information that can break a case wide open.
"The process now is to whittle down to try and find key words, key phrases that will link investigators to one of those pages where relevant information might be found," says CBS Security Consultant Ross Rice.
Rice also says police will be relying heavily on tips from the public to lead them to a clue, any clue that could help in the investigation. Rice says he anticipates this investigation is far from over.
Several schools in the Fox Lake area were closed Wednesday, because of the active search. The schools that were closed on Wednesday include Grant Community High School, Fox Lake Grade School District 114, Gavin School District 37, Big Hollow School District 38, and St. Bede Catholic School.
Grant Community High School, Fox Lake Grade School District 114, Gavin School District 37, Big Hollow School District 38 will be back open on Thursday.
Gliniewicz, a 30-year veteran of the department, was on patrol Tuesday morning around 7:50 a.m., when he radioed that he was checking out suspicious activity. A short time later, he told dispatchers he was chasing three suspects on foot, but radio contact was lost soon after, and when other officers arrived to back up the lieutenant, they found him shot in a marshy area near Route 12 and Sayton Road. He died at the scene. Police said his gun was not in its holster, but was found at the scene.
The Lake County Sheriff's office led a search for the three suspects on Tuesday, prompting schools in the area to go on various levels of lockdown, and affecting Metra commuter trains in the area. Several neighboring police departments and federal law enforcement agencies assisted in the manhunt. Late Tuesday night, the Lake County Sheriff's Office said it had turned over the search to the Lake County Major Crimes Task Force.
Gliniewicz, 52, a father of four, was set to retire at the end of the month. Many in Fox Lake knew him as G.I. Joe, and the community was mourning the loss of a man they admired, and who made them feel safe.
In more than 30 years on the Fox Lake Police Department, he had helped build the Fox Lake Police Explorer Post 300, which gives teens and young adults the opportunity to learn police skills.
"He meant something to this community. He made it a better place. You felt comfortable," said friend Zachary Point.
Fox Lake Mayor Donny Schmit said he had met Gliniewicz on Monday to discuss his plans to retire from the department, and his desire to make sure the Explorer Post would continue after he left the job.
"Not only did Fox Lake lose a family member, I lost a very dear friend," he said. "The coming days will be even more difficult as we remember him as a police officer, a father, and a member of our community."
Hundreds of mourners gathered for a memorial vigil for the lieutenant at Lakefront Park, 71 Nippersink Blvd. Black and purple bunting has been hung outside the Fox Lake police station, where a growing memorial has been set up to pay tribute to Gliniewicz.
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