The legal net tightened Thursday on militants involved in armed standoffs in Nevada and Oregon as federal prosecutors levied fresh charges against two more Bundy brothers and 12 others across the country.

The defendants all face accusations that they were mid-level leaders or gunmen in the 2014 Nevada standoff involving rancher Cliven Bundy.

Three of them also face separate earlier charges in the occupation of the Malheur National Wildlife Refuge in eastern Oregon.

They are Brian D. Cavalier, 44, of Bunkerville, Nevada, Blaine Cooper, 36 of Humboldt, Arizona, and Joseph D. O'Shaughnessy, 43, of Cottonwood, Arizona. Cavalier and Cooper already are in custody in Oregon. O'Shaughnessy, released from custody on the Oregon charge, was arrested Thursday in Phoenix.

They were named in a 16-count indictment filed Wednesday in U.S. District Court in Las Vegas by U.S. Attorney Daniel Bogden. Federal agents made arrests in five states Thursday on charges of conspiracy, using a firearm in a crime, assault on a federal officer, threatening a federal officer, obstruction of justice and extortion.

The 64-page document recounts in detail the efforts of agents from the U.S. Bureau of Land Management to impound about 400 cattle left out on public land by Cliven Bundy and the subsequent standoff in April 2014. Federal agents gave up after they were confronted and threatened by scores of armed militia members who cornered them in a wash near Bunkerville, Nevada.

The Nevada indictment is separate from federal criminal charges filed in Oregon against 25 people in connection with the refuge takeover.

Cavalier and Cooper were among the first armed protesters to seize the wildlife refuge, acting on Jan. 2 after a rally in Burns to protest federal land management and the imprisonment of two local ranchers. Cavalier acted as a bodyguard for the occupation's leader, Ammon Bundy, and Cooper was one of the occupation leaders throughout. O'Shaughnessy arrived later at the refuge and at one point set up an emergency medical tent nearby.

The refuge takeover largely came to an end with the Jan. 26 arrest of most of its leaders, but the bird sanctuary remained occupied by four protesters until they surrendered Feb. 11.

The new Nevada indictment accuses Cavalier, Cooper and O'Shaughnessy of helping "organize the gunmen" who confronted the BLM agents in Nevada. Cavalier and Cooper conducted reconnaissance missions, protected the Bundy family and created armed checkpoints to keep federal authorities at bay, the indictment said. O'Shaughnessy led gunmen to assault and extort federal law enforcement officers where the cattle were held, the indictment said.

The indictment also charged three others with roles in the Nevada standoff who had at times appeared at the Oregon wildlife refuge. They have not been charged in Oregon. They included Melvin D. Bundy, 41, of Round Mountain, Nevada, who joined brothers Ammon, 40, of Emmett, Idaho, and Ryan, 43, of Mesquite, Nevada, in the early days of the refuge occupation. The new indictment charged him with being one of the "leaders and organizers" of the Nevada standoff.

The Nevada indictment also named Todd C. Engel, 48, of Boundary County, Idaho, as one of the gunmen who helped force federal agents to flee the cattle impoundment in Nevada. He was one of four Idaho residents arrested Thursday on the new charge.

Engel is part of the Idaho Oath Keepers, a self-styled patriot group. Stewart Rhodes, president and founder of the national Oath Keepers organization, described in an online post how Engel traveled to the Oregon wildlife refuge nearly four weeks into the occupation to scope out law enforcement. Rhodes wrote that Engel and another Oath Keeper evaluated the strength of federal and state police resources and met on Jan. 23 with Ammon Bundy and Cavalier, known as Booda, to share their findings.

"They warned Ammon and Booda that all the assets were in place for a federal cordon or raid, and that they estimated that within a few days (two to three) the FBI would make a move to shut them down," Rhodes wrote. He said Bundy was encouraged to take security measures, such as setting up a cordon and ending appearances at public meetings.

Rhodes wrote that the next day, he and Engel talked with Robert "LaVoy" Finicum, 54, who often appeared as the public spokesman for the refuge takeover. Rhodes said he and Engel shared the security assessment with Finicum "to encourage him to make a move to that strongest position possible - a county with a constitutional sheriff."

Rhodes said he and Engel urged the move for the armed militants "not realizing they had already scheduled a meeting with Sheriff Glenn Palmer of Grant County." Palmer is considered by patriot groups to be a "constitutional sheriff" who will use his office to protect residents against federal intrusion. Palmer earlier had met with some of the refuge protesters and had urged the federal government to give in to some of their demands.

Two days later, on Jan. 26, Finicum and other occupation leaders left the refuge, bound for John Day and a community meeting where they were scheduled to speak. When FBI agents and state troopers stopped two vehicles carrying the leaders, Finicum repeatedly said they were going to a meeting with Sheriff Palmer. He was shot and killed on U.S. 395 about 20 miles north of Burns when he tried to evade arrest.

The new Nevada indictment also named Gerald A. DeLemus, 61, of Rochester, New Hampshire, accusing him of being a mid-level leader of the Nevada standoff. The indictment said he "trained and provided logistical support to gunmen" during the standoff.

DeLemus is co-chair of Veterans for Trump in New Hampshire. He traveled to the Oregon refuge just days after the occupation for meetings with Ammon Bundy. He said at the time he hoped to negotiate with Bundy and encourage him to give up the refuge occupation.

A fourth Bundy son, David H. Bundy, 39, of Delta, Utah, was charged in the new indictment as well. He was accused of being one of the "leaders and organizers" of the Nevada standoff who recruited gunmen, led an armed assault against federal officers, and made "extortionate demands" on them.

Four other leaders of the Oregon occupation already face charges in both Oregon and Nevada: Ryan and Ammon Bundy, Ryan W. Payne, 32, of Anaconda, Montana, and Peter T. Santilli Jr., 50, of Cincinnatti. Cliven Bundy faces charges only for the Nevada standoff.

Others charged in the new indictment include Eric J. Parker, 32, of Hailey, Idaho, O. Scott Drexler, 44, of Challis, Idaho, Steven A. Stewart, 36, of Hailey, Idaho, Richard R. Lovelien, 52, of Westville, Oklahoma, Gregory P. Burleson, 52, of Phoenix, Arizona, Micah L. McGuire, 31, and Jason D. Woods, 30, both of Chandler, Arizona.

-- Les Zaitz

@leszaitz