The company countersued Harmon, protesting the sale of his home to his son for $26,000 and asking a judge to prevent Harmon from getting rid of other assets. Harmon said the company's claims that the home was fraudulently transferred to his son were unfounded.
Harmon represented himself in the lawsuit, and Hummels represented Fusion.
Colleagues of Hummels described him as a smart, competent and decent man who was a rising star in his profession and dedicated to his wife, 9-year-old daughter and 7-year-old son.
"This is a day of just unspeakable sorrow," said 9th U.S. Circuit Court of Appeals Judge Andrew Hurwitz, who hired Hummels straight out of law school to serve as a law clerk from 2004 to 2005 while Hurwitz was serving on the Arizona Supreme Court.
The shooting took place in the building where pro tempore Judge Ira Schwartz, who scheduled the mediation, has an office.
The response to the shooting first centered on that building — home to insurance, medical and law offices — but soon spread to a north-Phoenix home and a central-Phoenix high-rise where Hummels' office is located.
SWAT teams and two armored vehicles surrounded the house. Police served a search warrant to enter the home, which county property records show was sold by Harmon to his son last year for $26,000.
For a time, officers used a megaphone to ask Harmon to surrender, believing he might be inside the residence.
Harmon's body eventually was found near a shopping area about 14 miles from the office building where Wednesday's shooting occurred. Police didn't immediately know how long it had been there.
The shooting took place on the same day that hearings on legislation to address gun violence were convened in Washington, with former Arizona Rep. Gabrielle Giffords testifying for stricter gun controls. A gunman shot Giffords in the head during a shooting rampage in Tucson in January 2011.