While police have vowed to utter the name of the suspected Virginia Beach shooter only once out of respect to the victims, many of those who’ve had personal interactions with long-time city worker DeWayne Craddock will likely have a harder time forgetting it—especially since they say he gave no signs of the impending carnage that would leave 12 of his coworkers dead.

Even moments before the shooting broke out just after 4 p.m. on Friday, Craddock wished a co-worker a good day during a chance encounter in the bathroom.

“I said, ‘How are you doing?’ He said he was doing OK,” Craddock’s former co-worker Joseph Scott told CNN. “I asked, ‘Any plans for the weekend?’ And he said, ‘No.’ I said, ‘Well, have a good day.’ And he said the same to me.” Scott said he left the office for the day following the conversation.

It was after that conversation that police say Craddock opened fire “indiscriminately” on multiple floors of the building, stopping only when police fired back, killing him, after he allegedly shot an officer.

Why Craddock, a civil engineer who had been with the coastal city’s Department of Public Utilities for almost 15 years, allegedly gunned down his coworkers is still unknown. While some reports have described him as a “disgruntled” employee, Police Chief James Cervera on Saturday disputed claims that Craddock had been fired before the shooting, stressing that he was still employed at the time of the attack.

City officials have declined to release information from Craddock’s personnel file, but a source quoted by The New York Times on Saturday said there were no warning signs in his behavior until recently, when he allegedly started getting into “scuffles” with other city employees.

In the past week, the source said, Craddock was warned that disciplinary action would be taken against him following an altercation, according to the Times.

Prior to the rampage, Craddock had no criminal history apart from several traffic violations over the years, court records show.

He graduated with a degree in civil engineering from Old Dominion University in Virginia, and enlisted in the Virginia National Guard in 1996. As part of the guard, he was assigned to the First Battalion, 111th Field Artillery Regiment, in Norfolk, Virginia, as a cannon crew member, according to a state National Guard spokesman. He was discharged in 2002 at the rank of specialist for reasons the National Guard would not disclose.

Neighbors have described Craddock as a quiet man who showed no red flags but tended to keep to himself.

“He said he worked for the city,” neighbor Christian Coble told The Washington Post, saying Craddock was “humble” and “average.”

“He seemed like an all right dude. I guess you never know what someone is going through,” he said.

Neighbors told local reporters Craddock was a member of the neighborhood association board and that his wife had left him some years ago.

Cassetty Howerin lived directly below Craddock and told CNN he was regularly awake during all hours of the night. “You heard him walking around; he would drop stuff at like 2 a.m., and me and my roommate would try to figure out what he was doing,” Howerin said.

By the time Howerin would wake up and leave at 7 a.m., he was gone. “I never saw him take trash out, never saw him bring groceries in, never saw people coming in or out," she said. “He was very to himself.”

Craddock’s former co-worker, Scott, told CNN he’d always viewed him as a “good person.”

“He was what I thought was a good person. When we were together, we would talk about family, friends, things that we were going to do, trips we were going to take and things like that.”

Craddock’s relatives have yet to speak out about the shooting, but in a handwritten note taped to the door of the family’s home in Yorktown, they offered their condolences to the victims.

“The family of DeWayne Craddock wishes to send our heartfelt condolences to the victims. We are grieving the loss of our loved one. At this time we wish to focus on the victims and the lives loss during yesterdays (sic) tragic event. Our thoughts and prayers are with the families of those who loss (sic) their lives, and those recovering in the hospital,” the note read.

As of Saturday afternoon, three of the four surviving victims were in critical condition.