A Boston man with links to the “extremist ideology” of the right-wing sovereign citizen movement was arrested after he was found to be in possession of a loaded firearm, a bulletproof vest, and chemicals often used to make explosives, federal authorities say. The man, identified as 47-year-old Pepo Herd El, was taken into custody on Thursday night. He was said to be wearing a security jacket at the time he was taken into custody, even though he does not work as a security guard, and authorities say he recently purchased spy cameras, a police patch, and hats featuring Home Depot, Amtrak, and AT&T logos. Agents who searched his home also found chemicals often used to make explosives, though they said they did not find any actual explosives. El, who has been the subject of police surveillance, was charged with one count of being a felon in possession of a firearm and ammunition and is scheduled for a Dec. 2 hearing.