Hummels was admitted to the Arizona bar in 2005.
"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.
According to court documents, Harmon was scheduled to go to a law office in the building where the shooting took place for a settlement conference.
Harmon represented himself in the lawsuit, and Hummels represented Fusion.
Fusion said Harmon was paid nearly $30,000 under the $47,000 contract. But the company asked him to repay much of the money when it discovered the cubicles couldn't be refurbished, according to the documents.
Harmon argued Fusion hung him out to dry by telling him to remove and store 206 "worthless" work stations after the mix-up was discovered. Harmon said Fusion then told him the company decided to use a competitor.
Harmon's lawsuit had sought payment for the remainder of the contract, $20,000 in damages and reimbursement for storage fees and legal costs.
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.
Osborn Maledon said Friday that services for Hummels are scheduled for Tuesday at the Orpheum Theatre.
The firm said donations can be made to the Mark Hummels Memorial Fund at the Arizona Community Foundation. Arrangements will be announced for an educational fund for Mark's minor children, the law firm said.