The deranged DC doctor who gunned down his condo’s building manager and wounded four others before turning the gun on himself, seemed to be doing “very well’ and was due to start a new job next week, his attorney revealed Thursday night.

Despite being locked in a bitter legal battle over his moldy $1.1 million Logan Circle penthouse, Dr. Matt Lambert seemed in good spirits, his civil attorney Joel Braithewaite told reporters Thursday.

“By all accounts, he was doing very well,” Braithwaite said, according to the Washington Post.

Braithewaite last spoke with Lambert, 55, on Tuesday, noting that the gunman gave a presentation on artificial intelligence in Orlando earlier this week – and was slated to start a new job on Monday.

“I’m at a loss as to how things took any sort of turn that has us here today,” he said.

Lambert shot and killed building manager James Stuart, 46, in the luxury condo’s gym Thursday morning before wounding four others — including one who remains in critical condition.

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

The crazed killer then holed himself up in his 7th floor penthouse for nearly an hour in a tense standoff with police before turning the gun on himself.

Stuart, who was “a central fact witness” in the doc’s civil litigation against the posh building, “was also very pivotal in relaying information to the [apartment housing] board,” the attorney said.

Eerily, Thursday marked the anniversary of Lambert’s mother’s death, Braithewaite said.

“I don’t know how all of those things coalesce. But unfortunately, this is a choice that I hope that my clients would never make,” the attorney noted.

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