Shooter, 70, was found dead from an apparent self-inflicted gun wound Thursday.

PHOENIX -- The second victim in Wednesday's shooting in an office complex in north-central Phoenix has died.

Mark Hummels, a partner at Phoenix law firm Osborn Maledon, was shot in the neck and back when Arthur Douglas Harmon, 70, opened fire on Hummels and Steven D. Singer after an arbitration meeting.

Singer, a 48-year-old father of two and CEO of Scottsdale-based Fusion Contact Centers LLC, died hours after the 10:30 a.m. shooting.

STORY: Phoenix office shooting claiming second victim

Harmon, whose body was found Thursday, appears to have died of a self-inflicted gunshot wound, Phoenix Police Sgt. Steve Martos said. Harmon's vehicle, a rented Kia Optima, also was found in the area.

Late Thursday, Hummels, a 43-year-old husband and father of two sons died, according to a statement from his law firm.

"We are devastated at this news about our beloved friend," according to a statement from Osborn Maledon on Thursday.

Osborn Maledon partner Bill Maledon said Thursday afternoon that Hummels was on life support, but that he would not survive his injuries. He deferred questions regarding donation of Hummels' organs to family, saying he did not feel comfortable speaking for them.

"They are making the determination when they can pronounce him dead," Maledon said.

Nichole Hampton, director of human resources at MD Home Health LLC, another office in the complex had gone outside to take pictures for business purposes and was caught in gunfire near the building entrance. She was hospitalized with a wound to her hand.

Police said a shot was fired at a fourth victim who pursued the shooter from the scene, but the person was uninjured. Two other people also were taken from the scene to a hospital with unspecified medical issues related to the shooting.

Rich Robertson, a private investigator, received a phone call from Mark Hummels at 8:30 a.m. Wednesday.

Hummels wanted a favor. He was calling to ask Robertson to assist one of Hummels' former clients, for whom he had provided free legal aid. Hummels was concerned the person needed more help, Robertson said.

"Mark was always willing to help," Robertson said.

Although Hummels had been an attorney for less than 10 years, he was already the president of a federal Bar group, had spent hundreds of hours providing free legal aid and had garnered the respect of many of Arizona's most prominent lawyers.

An hour later, at 9:30 a.m., Hummels was representing the chief executive of a call-center company at an arbitration meeting at a north-central Phoenix law office. Steven D. Singer, CEO of Fusion Contact Centers, was the defendant in a lawsuit. After the meeting broke up an hour later, both men were shot in front of the building.

According to court records, Singer had hired Harmon's firm almost a year ago to refurbish and move office furniture at the Santa Maria, Calif., offices of his call center, Fusion Contact Center LLC.

The contract was for $47,000, but a dispute erupted because not all of the work could be completed. The parties traded lengthy emails. In April, after receiving $30,000, court records say, Harmon filed suit.

As the legal case dragged on, court records say Harmon engaged in financial transactions with a son, Stefan Harmon. Legal filings allege that Arthur Harmon sold his home, valued at $100,000, to the son for $26,000, then borrowed $180,000 from another party using the home he no longer owned as collateral. The filings say that money then was loaned to Stefan Harmon.

Fusion countersued, alleging that Arthur Harmon, who had no legal counsel, was overpaid and fraudulently transferred property in connection with the litigation. The company sought a payment of $20,184 from Harmon to end the case. Harmon testified his savings totaled $17.

Mediation proceedings were set up to address continuing issues in the case.

Praise and respect for Hummels came from every corner, from those who knew him in Arizona legal circles to those who remembered him fondly from years before.

"He wasn't full of bluster. He would go out of his way for people," Robertson said.

Hummels worked as a journalist before becoming a lawyer. After receiving a bachelor's degree from Colorado College, Hummels earned a master's degree in journalism from the University of California-Berkeley in 1997. His first job was as a reporting -- intern in Santa Fe for the New Mexican.

"The best thing about Mark was his attitude. He was a serious journalist but made what we do fun," said Steve Terrell, a reporter with the paper. He and Hummels covered the New Mexico Capitol beat together. "When he became an attorney, we all teased Mark about how serious he looked in his work photo. We have a picture from his going-away party when he was wearing a Hawaiian shirt, smoking a fake cigar and crossing his eyes."

Hummels left the New Mexican in 2001 to attend law school at the University of Arizona. He graduated summa cum laude in 2004 and earned the highest score on the Arizona Bar exam that year.

Judge Andrew Hurwitz of the 9th U.S. Circuit Court of Appeals gave Hummels a job as a clerk when Hurwitz served on the Arizona Supreme Court in 2004.

He said that he and Hummels "became fast and dear friends."

"This is a day of unspeakable sorrow," he said. "We all feel so helpless."

Contributing: Arizona Republic reporters Lindsey Collom and Dawn Gilbertson