More details about DeWayne Craddock, the Virginia Beach civil engineer who killed 12 people and wounded nearly half a dozen others (including a police officer) on Friday during "protracted gun battle" inside the municipal building where he had worked, have started to emerge over the weekend.

And from a series of interviews with those who had worked with Craddock, a vague understanding of what may have been his motive has started to emerge.

DeWayne Craddock

While Craddock had no history of violence at work or in his personal life, according to the New York Times, he had been involved in a violent incident in the workplace in recent weeks, and had been warned that disciplinary action would be taken.

City officials including City Manager David Hansen said Craddock "was still employed" by the city at the time of the attack. "He had a security pass like all employees had and he was authorized to enter the building."

However, the Washington Post reported Sunday morning that Craddock had resigned from his position by email Friday morning, just hours before the shooting began.

Despite having no history of aggressive behavior, Craddock had begun acting strangely in recent weeks, even getting into "scuffles" with other works. He had even got into a violent altercation on city grounds, and was warned that disciplinary action would be taken.

Though his motives weren't clear, his neighbors had told reporters on Saturday that Craddock's wife had abruptly left him in the not-too-distant past.

When he stormed Building 2, the building where he had worked for more than a decade, helping to manage the city's water and sanitary sewer system, Craddock was armed with two .45-calber hand guns, at least one of which was outfitted with a silencer, and loaded with extended magazines. Two more guns were later found inside his home.

Police have yet to comment on a possible motive, and the reasons behind Craddock's sudden lurch toward staggering violence remain unclear.