The 40-year-old Virginia Beach civil engineer who shot and killed 12 people, including 11 colleagues, gave two weeks’ notice from his job hours before he opened fire in the building where he worked, officials said Sunday morning.

It was not immediately clear why DeWayne Craddock resigned from his post in the city’s Department of Public Utilities where he had worked for 15 years and what he wrote in his resignation email, which was sent to his chain of command Friday morning.

City Manager Dave Hansen said authorities were still working to recover a copy of the email, but Craddock had not been forced to resign. He had not gone to work that day, authorities said.

Investigators were working to reconstruct how he spent his day before he arrived at the government complex around 4 p.m., armed with handguns he had purchased legally and opened fire.

At a press conference on Sunday morning, Hansen said Craddock’s work performance was “satisfactory.”

“He was not terminated and he was not in the process of being terminated,” Hansen said, adding that he did not face any disciplinary measures before giving his notice.

“He was in good standing within his department,” Hansen said. “No issue of discipline ongoing.”

Virginia Beach Chief of Police James Cervera gave a detailed recreation of the incident and the complexity of the crime scene, calling the building a “honeycomb” in the way it was laid out, which he said made finding the shooter challenging.

Cervera said his officers, who were not equipped with body cameras, received the call at 4:08 p.m., the first officers arrived within two minutes and had engaged with Craddock within ten minutes.

“The time of dispatch to custody was 36 minutes,” Cervera said, meaning the gun battle with police lasted roughly 20 minutes.

Cervera added that his officers did administer first aid to Craddock once he had been shot but were unable to revive him.

Hansen said there would be a significant memorial service scheduled in the coming days.