Promising lead in Fox Lake officer's slaying comes up empty

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DNA From 'Unknown Donor' Found At Fox Lake Crime Scene

FOX LAKE, Ill. (WGN) -- Investigators say three men seen in a video from a home near where a northern Illinois police officer was shot and killed were not involved in the slaying.

Tuesday's announcement by the leader of the task force investigating last week's killing of Fox Lake Police Lieutenant Charles Joseph Gliniewicz puts to rest what authorities said was a promising lead into the identities of the suspects.

SEE MORE: Funeral of Illinois police officer draws hundreds of mourners

Lake County Major Crime Task Force George Filenko says investigators questioned the three men in the video and are confident they were not involved in the slaying.

Filenko said investigators were working to identify DNA from an "unknown donor" found at the scene.

Gliniewicz was found shot to death Sept. 1 in a remote area shortly after he radioed that he was pursuing three suspicious men.

On Monday, Gliniewicz was laid to rest with full military honors.

See more images from the funeral:

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Illinois cop funeral Lt. Charles Joseph Gliniewicz
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Promising lead in Fox Lake officer's slaying comes up empty
Jeff Jacobs of the Illinois State Police and Leroy Pugesek of the Lake County Sheriff's Office hug outside the funeral of slain Fox Lake police Lt. Charles Joseph Gliniewicz at Antioch Community High School on Monday, Sept. 7, 2015 in Antioch, Ill. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
Covered in an American flag, the casket of slain Fox Lake police Lt. Charles Joseph Gliniewicz arrives at Antioch Community High School on Monday, Sept. 7, 2015 in Antioch, Ill. The man in the maroon beret is Lt. Gliniewicz's son. Thousands of police officers and residents are expected to attend his funeral later this morning at the school. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
Hundreds of people get in line to pay their respects to slain Fox Lake police Lt. Charles Joseph Gliniewicz at Antioch Community High School on Monday, Sept. 7, 2015 in Antioch, Ill. Thousands of police officers and residents are expected to attend Gliniewicz's visitation and funeral today. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
Ron Flug, foreground, ride captain of the Patriot Guards leads the group to Antioch High School for the funeral of Fox Lake police Lt. Charles Joseph Gliniewicz on Monday, Sept. 7, 2015 in Antioch, Ill. (Brian Nguyen/Chicago Tribune/TNS via Getty Images)
Law enforcement officers salute the casket of Fox Lake police Lt. Charles Joseph Gliniewicz as it is wheeled into Antioch Community High School on Monday, Sept. 7, 2015 in Antioch, Ill. (Brian Nguyen/Chicago Tribune/TNS via Getty Images)
Covered in an American flag, the casket of slain Fox Lake police Lt. Charles Joseph Gliniewicz arrives at Antioch Community High School on Monday, Sept. 7, 2015 in Antioch, Ill. Thousands of police officers and residents are expected to attend his funeral later this morning at the school. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
A memorial is in place at the Fox Lake Police Department on Sept. 2, 2015 in Fox Lake, Ill. Police are searching for a second day to locate three suspects in the killing of Fox Lake Lt. Charles Joseph 'G.I. Joe' Gliniewicz. (Jose M. Osorio/Chicago Tribune/TNS via Getty Images)
Tara England of Ingleside and her 11 year-old son pray in front of the memorial for slain Fox Lake police Lt. Charles Joseph 'G.I. Joe' Gliniewicz on Wednesday, Sept. 2, 2015 in Fox Lake, Ill. Three suspects still remain at large and a manhunt is underway in the area. (Stacey Wescott/Chicago Tribune/TNS via Getty Images)
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A visitation and funeral was held at Antioch Community High School.

His casket was taken on an 18 mile long procession past a community of mourners who lined streets to pay their last respects.

Lieutenant Gliniewicz is buried at Hillside East Cemetery in Antioch.

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