DC Gym Gunman Identified as Doctor With Long Feud Over Mold and Water Damage, Police Say

Police in Washington, D.C., have identified the suspect in a gym shooting that killed building manager James Stuart as Matt Wade Lambert, a 55-year-old medical doctor. According to court documents, Lambert harboured a long-standing grievance with his building's condominium association and management and had taken legal action over water damage and mold.

Police said Lambert opened fire inside the gym, killing Stuart and injuring several others. Officials said one of the injured was critically wounded. Lambert then fled to his apartment, fired at more people from his balcony and later turned a gun on himself. Interim Metropolitan Police Chief Jeffery W. Carroll told a press conference on Thursday that Lambert died following a self-inflicted gunshot wound after barricading himself inside his apartment.

Carroll cited the building dispute as a possible motive for the shooting. Authorities said they were aware of an ongoing dispute between the suspect and the building condo homeowner's association management regarding maintenance issues and mold. Negotiators who spoke with the suspect mentioned that most of the conversation was about the homeowner's association and its challenges, Carroll said.

In March 2025, Lambert filed a complaint against his condominium association in the Superior Court of the District of Columbia, alleging mold and moisture and accusing the association of negligence, among other counts. The building's management, EJF Real Estate Services Inc., was also listed as a defendant in an amended complaint.

In response to the amended complaint, the condominium association and EJF Real Estate Services offered several affirmative defences, including that the plaintiff had failed to state a claim upon which relief can be granted and that the defendants did not owe a duty of care to the plaintiff on the issues alleged. ABC News has reached out to an attorney who was representing the Metropole Condominium Association in the dispute.

In a statement to ABC News, EJF Real Estate Services remembered James Stuart as a respected and beloved member of its team. The company said Stuart lost his life in a senseless act of violence. It said the investigation is ongoing and it would not comment on the details of the investigation.

Lambert appeared to operate an account on X since September 2025 focused on his alleged housing issues. The posts include numerous photos and videos he claimed showed water damage and mold in his unit, and what he alleged were his attempts to seek redress with his building's management. In at least one post, he appears to reference James Stuart, the man police say he fatally shot.

On May 19, he wrote that he saw his building manager at the gym that day and the manager stated no knowledge of the audit. On October 1, in a post referencing Luigi Mangione, he wrote that after months of delay, deny and defend tactics by the HOA, an independent engineering report had finally been submitted into the record. He said the report addressed unit 704, the facade rehabilitation more broadly and other affected units. A post referencing that report appeared on the account shortly after 8 a.m. on the morning of the shooting.

Lambert had also taken his grievances to the media. Reporter Michael Brice-Saddler, who previously interviewed Lambert about the dispute, told ABC News on Thursday that Lambert felt he had been wronged, felt he should not have to pay for mistakes he believed were the fault of the building, and tried to prove that through court.

Joel Braithwaite, an attorney for Lambert, told ABC News affiliate WJLA on Thursday that he was shocked by the events. He said Lambert had recently gained new employment and days earlier had presented at a conference on artificial intelligence and healthcare. Braithwaite said Lambert was not someone who, to his mind, would possess destructive intent or ill will towards anyone, and that he was very shocked and saddened to be having the conversation.