Gas prices around the District have been hovering at or above $4 a gallon for a while, and city officials are starting to wonder whether they should be a bit lower. D.C. Attorney General Irv Nathan says his office has launched an antitrust investigation into Capitol Petroleum Group LLC, owner of about half the gas stations in the city (and also a player in the market for getting fuel from oil companies to stations).

Yes, the company does own (but not operate) the notorious Watergate Exxon, home of prices high enough to get featured on TV news almost every week. But it’s a lot bigger than that. In February, Christine MacDonald profiled Joe Mamo, the owner of Capitol Petroleum, for Washington City Paper, looking into how he built a lease on one Amoco station on South Dakota Avenue into a regional empire:

Over the next quarter century—and in a manner more deliberate than accidental—he has built a network of stations around the region, acquiring them slowly, at first, and then, starting in 2009, at high speed. Riding a wave of industry transition, he went on a buying spree that expanded his empire from 25 to around 240 stations. Nearly half of all stations in the District are controlled by Mamo; he runs a quarter of the region’s stations.

He’s occasionally been painted as a rapacious tycoon, and sometimes been cast as an exemplar of the American Dream. In fact, Mamo may be a bit of both.

Read the whole thing here—it’ll shed some light into the investigation and the man at the center of it.

UPDATE: Mamo now appears to have a public relations firm working for him. This afternoon, his spokeswoman sent over a statement from Mamo and Capitol Petroleum on the antitrust investigation:

The high price of gasoline is of great concern to everyone. Twenty-five years ago as a struggling young worker, I saw an opportunity to be an entrepreneur and took significant financial risks to invest in a growing market. I started CPG in D.C. and have been servicing D.C. motorists for more than two decades. And while I’ve been successful and now own several dozen gas stations in the area, I simply own them—-I do not operate them and I do not set the price of gas at the pump. Nearly 90 percent of the sites I own are managed by individual franchisees. As a distributor, I purchase gasoline from major refiners which I then deliver and sell to the local operators. CPG and other distributors are prohibited by law from determining the prices at which their service station operators sell gas to the public. My mark-up has decreased over the past year and is not the cause of the high pump prices which I simply don’t control and which are set by each individual operator. In fact, the city makes more money on each gallon of gas than CPG does.

The unfortunate reality is that the price of gas is inflated by the world market and multiple other factors, primarily crude oil costs, taxes, refining costs, and distribution and marketing. There is a gross misunderstanding about the difference between a gas station owner and a gas station operator, and about how a gallon of gasoline is actually priced. I hope with education on the real issues at hand, we can put this matter to rest.

Photo by Darrow Montgomery