Investigators say three men seen in a video from a home near where a northern Illinois police officer was fatally shot 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.

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 are 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.