The jury was unable to reach a verdict on American Outlaws Association President Jack Rosga of Milwaukee, charged with conspiracy to commit racketeering and conspiracy to commit violence in the aid of racketeering for allegedly ordering Outlaws subordinates to ambush members of the Hells Angels in a war against the rival motorcycle club.
The defense argued those allegations were false, ridiculous accusations made by an Outlaws member who had sought to pad his own reputation, the Milwaukee Journal Sentinel reported.
Rosga, 53, who runs a trucking company, remained in federal custody pending a new trial requested by lead federal prosecutor Peter Duffey.
U.S. District Judge Henry E. Hudson said a new trial date would be set next week.
The jury convicted Leslie Werth, a leader in the club's Rock Hill, S.C., chapter, on the same charges facing Rosga. It also acquitted two other Outlaws members.
More than two dozen Outlaws members across the country were charged in Virginia June 15 with participating in a criminal enterprise.
The Outlaws Motorcycle Club, incorporated as the American Outlaws Association, is an alleged criminal motorcycle gang and reputed organized crime syndicate whose main rivals are the Hells Angels, giving rise to an acronym used by Outlaws members -- "ADIOS" for "Angels Die In Outlaw States."