PORTLAND — A federal jury Thursday acquitted the leader of the winter occupation of the Malheur National Wildlife Refuge and six others, in a big courtroom victory for the militant movement challenging federal control of public lands and a wrenching setback for federal prosecutors.

The jury found brothers Ammon and Ryan Bundy and five others not guilty of conspiring to impede federal workers from doing their jobs during the 41-day armed takeover that ended Feb. 11 at the refuge, some 300 miles southeast of Portland.

"This is off-the-charts unbelievable," said Matthew Schindler, an attorney for defendant Kenneth Medenbach. "I had been telling my client you can count on being convicted. You don't walk into a federal court and win a case like this. It just doesn't happen."

The trial stretched on through five weeks of lawyers' arguments and witness testimony, then days of jury deliberations that included a rare replacement of a juror accused of bias, before finally ending in a moment of drama and chaos.