(CNN) -- Three suspects remain on the lam, and while authorities continue to look for them in connection with a Fox Lake, Illinois, policeman's death, the search was called off Wednesday morning in the immediate area where Lt. Joe Gliniewicz was slain, police said.
This, after investigators had set up a 2-mile perimeter across tricky terrain and brought in helicopters, canine units, federal agents, night-vision equipment and body heat sensors. Police cleared every home in the cordoned-off area, while fielding more than 100 tips, Lake County Major Crime Task Force Commander George Filenko told CNN.
The suspects -- two white men and one black man -- may have left town, or even the state, Filenko said.
So far, police have found no witnesses, but they did recover surveillance tape. The quality of the video is not promising, but investigators were going through it Wednesday morning, Filenko said.
Hampering the search was the landscape where the manhunt unfolded. It's a mix of abandoned buildings, occupied by squatters, and residential and commercial properties situated among heavily wooded areas and a marsh. Some of the terrain is overgrown and swampy, and railroad tracks run through a portion of the area. Tuesday's intense sun didn't help matters.
Gliniewicz, a 32-year police veteran, was on patrol Tuesday morning when he made a radio call saying he was running after three suspicious people, the Lake County Sheriff's Office said.
That was the last time anyone heard from him. Fellow officers from Fox Lake Police Department arrived to find their colleague shot to death.
No one knows why Gliniewicz was gunned down, except for his killer.
A challenging search
The FBI, U.S. Marshals and the Bureau of Alcohol, Tobacco, Firearms and Explosives joined in the hunt. More than 100 law enforcement officers raked through the heavy woods near Fox Lake on foot, all-terrain vehicles and horseback.
Some had K-9 partners. Helicopters aided the search.
Nearby residents saw SWAT teams canvassing their yards, CNN affiliate WLS said. Officers also went house to house looking for clues.
"I hope they catch them soon," neighbor Brenda Day said, "because I'm a single mom of three, and I'm scared."
School officials were anxious, too. Several Illinois school districts, including Fox Lake, Gavin and Big Hollow, were closed Wednesday, the Grant Community High School website said.
More than an officer
Gliniewicz's passion for police work went far beyond what he was paid to do.
He helped lead the Fox Lake Police Department Explorer Post, which mentors young people interested in careers in law enforcement, WLS said.
Gliniewicz, known as "G.I. Joe," was supposed to retire at the end of this month. The day before he was killed, Gliniewicz met with the mayor to discuss his retirement plans and to make sure the Explorer program continued without him, according to WLS.
"He loved his community and loved his job, and he will be very sorely missed in this community," Grant Township supervisor Catherine "Kay" Starostovic said.
Gliniewicz was also an Army veteran who served in active duty and reserve from 1980 to 2007. He left the military with the rank of first sergeant.
The lieutenant is survived by a wife and four children.
His death marks the 26th time an officer has been shot and killed in the line of duty this year. Just last week, a sheriff's deputy in Houston was gunned down in an ambush attack.
"It is a very tough time to be a police officer at this moment," CNN law enforcement analyst Cedric Alexander said. "However, these men and women that are out there doing this job, they're not going to stop doing it."
A vigil for Gliniewicz is scheduled for 6 p.m. Tuesday at Fox Lake's Lakefront Park.
[findthebest id="lepiHu7KvI1" title="Officers Feloniously Killed in the Line of Duty Over Time" width="600" height="435" url="//www.findthebest.com/w/lepiHu7KvI1" link="http://places.findthehome.com" link_text="Officers Feloniously Killed in the Line of Duty Over Time | FindTheHome"]