The gunman who opened fire at a gym in a luxury condo building in Washington, D.C., Thursday morning had been complaining about mold and water problems in his apartment in the building. Multiple law enforcement sources have identified him as Dr. Matt Lambert.
Police said he shot and killed himself in his apartment after killing at least one person and wounding four others in what law enforcement sources said was a targeted attack.
Three firearms were recovered from his apartment, according to law enforcement sources in Washington.
An account on X under the name @OfMiceandMold has served as a repository for complaints about the alleged disrepair of the apartment where Lambert lived.
In dozens of X posts, he vented his frustration with the Metropole Condominiums’ building contractors, EJF Real Estate Services, and his allegations they failed to address problems with his unit. CBS News has reached out to EJF Real Estate Services for comment.
Lambert, who was 52 and ran a D.C.-based healthcare consultancy, had purchased the condo in September 2016 for $1,095,000, according to D.C. tax records. Court documents show he owned a penthouse unit in the building.
Before the shooting, he posted what he claimed was an engineering report that investigated mold and water issues in his building. “My manifesto is an engineering report,” he wrote.
At one point, he appeared to invoke Luigi Mangione, who shot and killed UnitedHealthcare CEO Brian Thompson in 2024. On Oct. 1, he wrote, “After months of ‘Luigi’ tactics (delay, deny, defend) by the HOA, we were finally able to submit an independent engineering report into the record,” and said he would share the engineering report on X “when the time is right.” Mangione had written “delay, deny, defend” on the bullets he used in the shooting.
In a social media post from April 28, he wrote: “If you’re looking for the building manager, I would check the gym.”
Lambert sued the Metropole Condominium Association, listing his grievances and alleging damages of more than $290,000 as of May.
The Metropole Condominium Association and EJF denied causing the damage and said any damage was caused by third parties beyond their control and that Lambert failed to limit his losses.
The Metropole Condominium Association and EJF did not immediately respond to requests for comment.
Police said he carried out the shooting inside the Vida Fitness center on the ground floor of the building, which caters to the building’s residents.
One woman said she was on a treadmill in the gym when she heard the shots fired. She described having to evacuate past the scene where one victim was killed.
“There was no way of getting out of the gym other than going past that scene,” she said.
“It was like chaos. It was horrific, honestly.”
A witness who was about 20 feet from the shooting told CBS News that he lived directly below Lambert, and described him as being increasingly upset at HOA meetings. He said Lambert used to invite people into his apartment to show them how bad it was. The witness called the building a “tight-knit community” with 99 units.
The witness said that during the shooting and standoff with police, his girlfriend barricaded herself in the apartment, which is now under an inch of water from the response to a fire at the scene.
Logan Circle is a vibrant neighborhood in Washington, D.C., gentrified in the 2010s, with historic architecture and some of the most popular restaurants and bars in the city.
Lambert was the founder and CEO of MLEM, a healthcare and technology consultancy, according to his LinkedIn profile. He obtained his undergraduate and medical degree at Marshall University in West Virginia, and completed his residency at West Virginia University, according to his profile.
