"We can confirm the individual in Mesa is in fact suspect Arthur Harmon. He was found deceased with a self-inflicted gunshot wound by Mesa PD," Phoenix police Sgt. Steve Martos posted on his Twitter account.
Mesa police Sgt. Tony Landato said a landscaper discovered the body shortly before 8 a.m, KTVK-TV, Phoenix, reported. Landato said a weapon was found near the body.
The Kia Optima Harmon was last seen driving was found in a parking lot and the body was found in some bushes nearby, KTVK reported.
Harmon was reported in a legal battle with a telephone call center. Phoenix police said they think Harmon targeted two men and shot another person after a mediation session at building in north-central Phoenix.
Killed was Steve Singer, 48, the call center's executive officer and a defendant in the lawsuit filed by Harmon. Singer's attorney, Mark Hummels, who sustained serious wounds to his neck and back, was not expected to survive, the law firm where he practiced said in a statement.
"Our friend and partner, Mark Hummels, was severely injured in yesterday's senseless shooting," the statement by Osborn Maledon read. "We have been informed that Mark will not survive from the shooting. We are devastated at this news about our beloved friend."
Bystander Nicole Hampton was shot near the building entrance, suffering a hand wound.
After the incident Wednesday, police searched Harmon's home and removed several items. Investigators did not elaborate on what evidence was collected.
A man who once worked with Harmon told KTVK Harmon "exhibited behavior in the past that would seem to be a little bit hostile and erratic. I think that those should have been a little bit more of a warning sign."