A landscaper in Mesa found the body of 70-year-old Arthur Harmon on Thursday. On Wednesday, one person died and two others were wounded in the shooting, which broke out at a law office in north-central Phoenix.
Authorities say the rental car Harmon was using was found in a parking lot near his body.
Police said the shooting was was not random. According to investigators, the suspect shot and killed the CEO of a company he had a dispute with and critically wounded the company's attorney, as well as another person.
The shooting happened at the end of a mediation session over a lawsuit Harmon filed against the company in a contract dispute.
The Associated Press contributed to this report.
