FAIRBANKS -- A judge has banned the use of more than 100 hours of electronic surveillance evidence in the murder conspiracy case against a Fairbanks militia leader.

The decision reported by the Daily News-Miner on Monday costs prosecutors a large quantity of evidence against Schaeffer Cox, whom they accuse of hatching a plot to kill Alaska State Troopers and court officials.

Superior Court Judge David Stewart said in his ruling that audio and video recordings made during a six-month FBI investigation into Cox and his Peacemaker's Militia are not admissible because they were made without a search warrant, and therefore violate the Alaska Constitution.

Prosecutors had argued the recordings should be allowed because informants who made them worked for the FBI, which has wider authority to obtain warrants.