Mamo has been in the spotlight since last spring, when the D.C. government launched an antitrust probe. (Mark Gail/The Washington Post)

As noted last month, D.C. Attorney General Irvin B. Nathan has backed off an antitrust investigation of Mamo’s gas station holdings in the District, and a D.C. Council bill that would have curbed his business model failed in February.

Mamo and his companies have also faced a high-stakes lawsuit in Alexandria’s federal court. Some two dozen gas station dealers who operate more than 160 stations in D.C. and Virginia have been suing Mamo since October, alleging racketeering, antitrust violations and other breaches of federal and state law.

They allege, among other things, that Mamo has attempted to force them out of business by raising their rents, locking them into a sole-source gasoline supply deal, not maintaining his properties and otherwise engaging in unfair business practices. The idea, the dealers say, is that Mamo would rather have his own contractors running the stations he owns.

But the suit’s chances have dimmed. Mamo won a major victory Friday, when U.S. District Judge Claude M. Hilton granted motions to toss out most elements of the station operators’ case.

It is unclear whether the dealers will appeal or otherwise continue pursuing the case; their attorney, Peter L. Goldman, did not immediately return a call for comment Thursday. But Mamo said in a statement that he’s “very pleased” with both the court rulings and Nathan’s decision not to pursue charges.

“These decisions just reaffirm what we have been saying all along — the price of gasoline is a function of the global market, and we have had nothing to do with the high prices at the pump,” he said, adding a thank you to his customers “who stood by us during all of this.”

Mamo added that he’s “glad to now be able to focus on our mission again — continuing to serve our customers in the greater Washington market as fairly as we have been doing for the last 25 years.”