Joseph O'Shaughnessy, known as "Captain'' in militia circles, said Monday he didn't participate in the occupation of Malheur National Wildlife Refuge, but admitted he provided security for those at the refuge because he supported their message.

O'Shaughnessy pleaded guilty in federal court in Portland to a single count of conspiring to impede federal employees from doing their work at the refuge through intimidation.

Assistant U.S. Attorney Craig Gabriel said a recommended sentence of 12- to 15- months in Oregon is expected to run concurrently with O'Shaughnessy's Nevada sentence.

"Although I did not participate in the occupation, I did support their message and felt a duty to provide security for these individuals,'' O'Shaughnessy told U.S. District Judge Anna J. Brown. "I'm aware it intimidated and prevented federal employees from doing their duties.''

O'Shaughnessy, 44, of Cottonwood, Arizona, is expected to face about six years in prison under a negotiated plea deal pending in Nevada.

His plea deal in Nevada was contingent on him pleading guilty in the Oregon case, according to attorneys involved in the case.

O'Shaugnessy is the 10th of 26 defendants to plead guilty to the conspiracy charge stemming from the 41-day occupation of the federal refuge outside Burns in Harney County. He's the fourth of seven defendants facing federal indictments in both Nevada and Oregon to accept global plea deals to resolve both cases.

He's now expected to be transferred to Nevada to enter a guilty plea and be sentenced there before returning to Oregon for a Dec. 2 sentencing in the refuge case.

The Nevada indictment stems from what authorities have described as an April 2014 "massive armed assault'' by rancher Cliven Bundy and his co-defendants to thwart federal officers who tried to corral about 400 cattle near the Bundy ranch in Bunkerville.

The Nevada indictment described O'Shaughnessy as a "mid-level" leader who helped "organize the gunmen" who confronted agents from the U.S. Bureau of Land Management attempting to impound Cliven Bundy's cattle. It also accused O'Shaughnessy of organizing armed patrols, security checkpoints and protection for members of the alleged criminal conspiracy in Nevada.

He's charged with more serious offenses in Nevada, including conspiracy to impede federal officers, assault on federal officers, threatening federal officers, using and carrying a firearm in a crime of violence, obstruction of the administration of justice, interfering with commerce by extortion and interstate travel in aid of extortion.

In Oregon, prosecutors have said that O'Shaughnessy came to Burns in late December and views himself as a captain with the Oath Keepers militia. On a Go Fund Me Page created on Aug. 11, 2014, O'Shaughnessy said he had retired from firefighting and paramedic work before taking on a role as "team Captain for AZ Militia.''

In earlier hearings, federal prosecutors in Portland presented photos and videos from O'Shaughnessy's Facebook page that showed him outside the refuge. One video played in court captured O'Shaughnessy, in his own words, talking about being in Burns to set up a "constitutional security protection force'' just four days into the armed occupation of refuge.

On another video, O'Shaughnessy appeared on independent broadcaster Pete Santilli's show urging others to support the occupiers even if they didn't support their tactics.

In the photos, O'Shaughnessy was dressed in tactical gear and armed with a rifle outside the refuge and setting up a bunkhouse for emergency operations and "QRF,'' military shorthand for "Quick, Reaction Force,'' prosecutors have said.

O'Shaughnessy's defense lawyer Amy Baggio has argued in the past that her client wasn't aware of the plan to occupy the refuge when he came to Burns and disagreed with Ammon Bundy and his followers' tactics to occupy the federal property. She even submitted letters to the court from co-defendants Ammon Bundy and his older brother, Ryan Bundy, who vouched that O'Shaughnessy disagreed with the refuge takeover.

O'Shaughnessy never spent a night at the refuge, but visited daily to try to convince the Bundys and other followers that what they were doing was "bad for the movement,'' his lawyer said. He also went to the refuge to serve as a "buffer'' in an attempt to de-escalate the situation and to "bear witness'' to any problems that might ensue with law enforcement, his lawyer had argued.

Prosecutors said they had no evidence that O'Shaughnessy stayed overnight at the refuge, but pointed out that O'Shaughnessy was recruiting others via video to come to the refuge and talked about setting up a "constitutional security protection force" to prevent agents acting like cowboys.

On Monday, Gabriel said only that O'Shaughnessy agreed with others to provide security to armed occupiers and intended through intimidation to keep federal law enforcement and employees from the U.S. Fish & Wildlife and U.S. Bureau of Land Management from entering the refuge and performing their work.

Counter protester Candy Henderson, who camped in a tent at the Narrows campground during the refuge occupation, said she saw O'Shaughnessy armed with guns at the compound on a daily basis.

"He tried to intimidate me everyday,'' Henderson said Monday. "He was part of the whole thing.''

Stewart Rhodes, president and founder of Oath Keepers, said O'Shaughnessy has never been a member of Oath Keepers nor held any leadership position in the organization. Yet Rhodes called the federal prosecution of O'Shaughnessy and his co-defendants "troubling,'' and the federal conspiracy charge "vague'' and too broad.

Ammon Bundy, the leader of the refuge occupation, and seven co-defendants are set to go to trial Sept. 7.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian