PHOENIX (CBS5) -
Angry, a bully, a nut job - those are the words used to describe the man who opened fire at a Phoenix office complex Wednesday.
According to police, Arthur Harmon, 70, opened fire at the office complex, killing two men and injuring several others.
CBS 5 News spoke to a number of people who had contact with Harmon in the past.
Harmon was in the middle of a civil dispute stemming from some work he was hired to do for a Scottsdale company called Fusion Contact Centers.
Two of the victims in the shooting were Fusion CEO Steve Singer and his attorney Mark Hummels.
CBS 5 News obtained some letters Harmon had sent to Hummels last year, during the course of the litigation.
"You lying sack of s***," Harmon wrote. "Hummels, you're nothing but a sleazy lowlife attorney trying to ave your stinking skin."
"You (expletive), son-of-a b***. I am going after you with every fiber in my being and I wont rest until I see you behind bars for conspiracy to defraud," said Harmon.
Valley attorney David Panzarella said he saw firsthand how erratic and abusive Harmon could be.
"Having phone calls and dealing with him, you knew from the beginning he was different," Panzarella said. "Our office staff called him a 'nut job.'"
Several years ago, Panzarella represented a client in a lawsuit involving Harmon, who was representing himself.
Panzarella said that he remembers Harmon acting paranoid with obvious anger issues, whose main objective seemed to be dragging out the legal process.
Hearing what happened Thursday had an immediate impact on Panzarella's entire office, the attorney said.
"It was sobering to recognize that a guy like that, who files so many lawsuits and feels like he is put upon, was eventually going to snap somewhere," Panzarella said. "The fact he could have snapped at our office is frightening to think about."
CBS 5 News learned that Harmon was connected to at least five civil lawsuits since 1994.
In each case, Harmon represented himself.
Copyright 2013 CBS 5 (KPHO Broadcasting Corporation). All rights reserved.
Arthur Harmon (Source: Phoenix Police Department)
