June 2 (UPI) -- The gunman in Friday's mass shooting in Virginia Beach had filed to leave his job before opening fire on his workplace, city officials said on Sunday.
The suspected gunman, Dewayne Craddock, a 40-year-old engineer who worked in public utilities for about 15 years, put in his two-week notice hours before he would carry out an attack on Virginia Beach Municipal Center in which 12 people were killed and he died in a shootout with police.
Virginia Beach city manager Dave Hansen said the suspect's job performance was "satisfactory" and that he hadn't previously faced any disciplinary measures prior to providing notification of his planned departure.
A Virginia government source had described the suspect as a "disgruntled employee."
Mayor Bobby Dyer said that authorities and the government were still searching for answers regarding his motive.
"I guess the big question is why? We want to know too," he said.
Forty members of law enforcement were collecting evidence at the site of the shooting in Building 2 of the municipal center as part of an investigation into the shooting.
The Federal Bureau of Alcohol, Tobacco, Firearms and Explosives said that the suspect legally purchased two .45 caliber handguns that were found at the scene, and police said one of the pistols found had a suppressor and several empty extended magazines.
One of the guns was purchased in 2016 and the other in 2018, and neither were used in any other crime, the ATF said.
Virginia Beach police chief Jim Cervera said more weapons were discovered at the suspect's home.
Police believe the suspect used the silencer for stealth as he opened fire throughout the building.
The suspect began by killing a victim in a car before entering the building and opening fire. All but one of the people killed in the shooting were public works department employees.