The deranged Washington, DC, doctor who gunned down his building manager Thursday over his moldy $1.1 million penthouse chillingly knew the victim’s morning routine — and name-dropped Luigi Mangione.

In an interview with a then-Washington Post reporter, Matt Lambert railed about the building manager-turned-slay victim James Stuart, saying the fight over the mold that turned his 7th-floor home into a hell hole had turned into “psychological warfare,” The Washington Sun reported Thursday.

He also eerily noted to a fellow resident who had also been waiting for repairs to be done to his apartment: “If you want to see the building manager he comes in the gym about 8 o’clock.”

Lambert used a handgun to kill Stuart just after 8 a.m. inside the building’s ground-floor gym in the ritzy Logan Square neighborhood.

The crazed killer also referenced Mangione, the UnitedHealthcare CEO killer, in conversations with the journalist, Michael Brice-Saddler, who penned a piece about his encounter with the now-dead ER doctor for The Washington Sun.

Last December, Brice-Saddler recalled Lambert mentioning the three words inscribed on Mangione’s bullets he used to kill Brian Thompson.

“What are they called? Delay, deny, defend … the Luigi three?” Lambert said at the time.

The DC gunman also mentioned Mangione on X, as he ripped management for dragging its feet on repairing the Logan Circle building.

Here’s the latest on the deadly shooting at a Washington, DC gym:

“After months of ‘Luigi’ tactics (delay, deny, defend) by the HOA, we were finally able to submit an independent engineering report into the record,” Lambert wrote on Oct. 1.

“The report addresses 704, the facade rehabilitation more broadly , and lists other units affected. When the time is right, I will share the report on X, with other Metropole owners, and with Logan Circle realtors.”

He also shot and injured four others from the balcony of his apartment.

Lambert killed himself in the mold-ridden penthouse following an hour-long standoff with cops.

This is a developing story. Please check back for updates.