The reason why DeWayne Craddock shot up a Virginia Beach municipal building on Friday - killing 12 people, and severely wounding four others - may have died with him.
Even as families plan funerals on Monday, Craddock, 40, remains a puzzle to police.
He left no note, internet message or manifesto, that police have announced. Police said he had no specific person as a target, shooting indiscriminately, including his first victim in a vehicle in the parking lot before he went inside.
He was ultimately shot and fatally wounded by police after a gun battle in the maze-like halls of a 1970s-era municipal building, Craddock at one time shooting through a closed door and wall.
Virginia Beach Police Chief James Cervera described Craddock as "disgruntled," but declined to say more about what may have precipitated the attack.
"We have more questions than we really have answers," he told reporters about two hours after the shooting on Friday.
Craddock declared his intention to quit by email in the morning and started shooting at his workplace of almost 15 years late that same afternoon, about 4 pm, before his co-workers clocked out for the weekend.
Craddock's bosses said that he was an employee in good standing, with no disciplinary actions pending and was not going to be fired, but they are still looking into it.
"To the extent that the subject's employment status has anything do with these events, that will be part of the ongoing investigation," City Manager Dave Hansen told reporters.
Craddock's parents posted a handwritten note on the front door of their Yorktown, Virginia, home on Saturday expressing sorrow and prayers for 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 yesterday's tragic event," the note said.
"Our thoughts and prayers are with the families of those who loss their lives, and those recovering in the hospital."
The hand-scrawled note states no reason for the shooting.
The mass shooting in the coastal resort of Virginia Beach was the deadliest instance of US gun violence since November, when a dozen people were slain at a Los Angeles-area bar and grill by a gunman who then killed himself.
An impromptu memorial set up at the municipal centre was visited by well-wishers on Sunday and media images show family and friends and holding hands and lighted candles at multiple churches from Baptist to Roman Catholic.
