Before Hiller was cornered and arrested, she also shot at several other employees and in the direction of two police officers.
On Monday, Hiller, 45, dressed in a flowing black Muslim garment, declined to testify on her own behalf during a nonjury trial at the city's Criminal Justice Center.
Common Pleas Judge Benjamin Lerner convicted Hiller of two counts of first-degree murder, one count of attempted murder and all related charges after hearing testimony from Dalton, a handful of other Kraft employees who witnessed the carnage and several police officers who responded to the scene.
Though Lerner set the formal sentencing hearing for Sept. 24, a first-degree-murder conviction carries a mandatory sentence of life in prison without parole. In exchange for Hiller's waiving her right to a jury trial, the District Attorney's Office withdrew the right to seek the death penalty.
"This case is a horrible, horrible tragedy," said Lerner, who added that it raised questions about how the mentally ill are treated and how a person in Hiller's condition could have been given a gun permit.
Defense attorney Constance Clarke argued that Hiller should be convicted only of voluntary manslaughter given what was going through her mind.
"She believed her co-workers were trying to poison her with chemicals. It was an unreasonable belief, but that is what Ms. Hiller believed," Clarke said.
Assistant District Attorney Gail Fairman said that Hiller hatched a plan to murder her victims and carried it out. "She was the aggressor. She was an angel of death, essentially, stalking those hallways," Fairman told Lerner.
After leaving the courtroom, Dalton and Terral Brown, LaTonya Brown's mother, said they wished that Hiller had gotten the death penalty.
"My daughter did not deserve to die like that," Brown said.
"Justice has been served," said Dalton, who returns to work later this week for the first time since 2010. A bullet remains in his shoulder. He said that he never had problems with Hiller before the shooting.
"I pray that she gets the help that she needs," he said, "and I'm grateful this will never happen to anyone else. She can't hurt anybody else."
Contact Mensah M. Dean at email@example.com or 215-568-8278. Follow him on Twitter @MensahDean.