LAS VEGAS — Federal authorities rounded up 12 people in five states on Thursday, bringing to 19 the number of defendants facing conspiracy, assault and threats charges in a 2014 armed standoff over grazing cattle on U.S. land near renegade cattleman Cliven Bundy’s ranch in southern Nevada.

Arrests of alleged co-conspirators in Arizona, Utah, Idaho, Oklahoma and New Hampshire came after a federal grand jury in Las Vegas expanded an indictment already filed against Bundy. It also names two adult Bundy sons and five other men already in federal custody following the end of a nearly six-week armed occupation of a wildlife refuge in Oregon.

Court documents accuse the men of leading more than 200 followers into an armed confrontation that forced federal Bureau of Land Management agents and contract cowboys to abandon an effort to corral and remove Bundy cattle from federal lands where he was accused of letting them graze for decades without paying federal fees.

At the family home in Bunkerville, Nevada, Cliven Bundy’s wife, Carol, acknowledged that her husband and sons Ammon, Ryan, Melvin and David Bundy were in federal custody. The mother of 14 adult children pleaded for prayer and echoed her husband’s call to fight government overreach.