Federal agents arrested a Dorchester man on gun charges and found various materials in his McLellan Street house last week that could be used to create explosives, the US Attorney’s office reported, adding that an investigation continues into his alleged “anti-government/anti-authority sovereign citizen extremist ideology.”

Pepo Herd El, also known as Pepo Wamchawi Herd (El), 47, was arrested at the Ruggles T stop after he got off a bus from Dorchester wearing a bullet-proof vest under a jacket with “Security” written on it and packing a loaded pistol, three spare magazines that were also fully loaded, and a knife, according to an affidavit filed by an FBI agent on the case. El was then charged with being a felon in possession of firearms because of two 2004 convictions in Massachusetts for unlawful firearms possession.

“The investigation remains ongoing,” the US Attorney’s office said.

At the same time as he was being arrested, other federal agents were raiding El’s house at 53 McLellan St., where they found “several of the household chemicals that they suspected El was using to create homemade explosives,” Live Boston reported, adding that agents also found details of recent purchases on eBay that included copper bars, rods and tubes, various acids, wire, magnesium shavings and balls, tungsten powder, and a hot plate with a magnetic stirrer.

In the affidavit, the FBI agent described some of those purchases: “EL has also purchased several chemicals through his eBay and Amazon accounts. Each of these chemicals has an innocent household or industrial use. However, several can also be used or combined to create incendiary or explosive compounds.

“For example, I have been advised that EL has purchased all of the chemical precursors necessary to produce black powder, an explosive that can detonate an improvised explosive device. Black powder requires three chemicals.

The first is potassium nitrate, which is found in Hi-Yield Stump Remover, a commercial product designed to remove tree stumps from soil. EL used his eBay account to purchase this product on or about June 2, 2020.

The second ingredient is sulfur, which EL purchased in powder form on that same day via eBay.

The third ingredient is charcoal, which El purchased using his Amazon account on or about December 2, 2019. Based on my training and experience, combining these three ingredients in specific ratios creates a low explosive chemical reaction.

“I further note that, on or about July 31, 2020, EL used his Amazon account to purchase 20 feet of model rocketry fuse. This material could be used to initiate black powder. When black powder is contained and initiated, it can detonate.

Additionally, adding fragmentation to this mixture could increase the damage it causes when it detonates. Air rifle pellet ammunition could serve this purpose. According to EL’s eBay records, between in or about May and July 2020, EL purchased at least 800 air rifle pellets, in addition to a pellet gun. Based on the substances and quantities listed above, explosive experts have informed me that EL has enough material to produce at least a pound of black powder, which could be used as an explosive in an improvised explosive device, such as a pipe bomb.

“El’s purchase history includes other fuels, oxidizers, and solvents. Some of these – such as magnesium, potassium permanganate, and iron oxide, all of which he purchased through his eBay account on or about June 2, 2020 – could produce incendiary compounds.

El also purchased a hot plate and stir bars, which are used to heat chemicals and to mix chemicals while they are heating. These are common techniques for increasing the speed and efficiency of chemical reactions.”

In a 15 1/2-hour search of the house, however, agents did not find any black powder or actual explosives, the affidavit continues. The affidavit continues that additional searches will likely be made because of how “disorganized and cluttered” the house is. Also, agents did not begin searching until bomb technicians spent 3 1/2 hours on their own search to make sure there was nothing about to blow up while other agents were conducting their search.

El’s last name is a common one among so called Moorish sovereign citizens - Black people who, like their more commonly known white counterparts, believe they are not subject to most laws. The Southern Poverty Law Center characterizes them as an extremist movement: “Recently, Moorish sovereign citizens have engaged in violent confrontations with law enforcement. They have also been known to retaliate against government authorities through financial means - a process called ‘paper terrorism.’

Moorish sovereigns espouse an interpretation of sovereign doctrine that African Americans constitute an elite class within American society with special rights and privileges that convey on them a sovereign immunity placing them beyond federal and state authority.”

According to the FBI agent’s affidavit, El used a common sovereign-citizen notation when signing for the property agents took when arresting him at Ruggles: “After being advised of his Miranda rights, EL was asked to sign a property receipt for the items seized from his person (including the Glock 27). In addition to his name, EL signed “UCC 1308.” I am aware from my training and experience that it is common for sovereign citizens to file numerous frivolous lawsuits and file claims using the Uniform Commercial Code (“UCC”). Section 1-308 of the UCC is a method of reserving one’s rights in a contract.”

El has ten “pins” on his Pinterest page, one a photo of a Kevlar bullet-proof vest, the other nine photos of messages about lawsuits and texts of articles about limits on federal powers.