On Saturday, the Scottsdale Police Department announced in another statement: “Our investigation has determined that this double homicide is related to the shooting of Steven Pitt.”

The Scottsdale Police Department also announced it was investigating a fourth homicide in the area. The police responded to a call just after midnight Saturday about a shooting at a business approximately halfway between the other killings, said Sgt. Benjamin Hoster, a spokesman for the Scottsdale Police.

The police did not know whether that shooting was related to the previous two attacks, Sergeant Hoster said. On Sunday, they identified the man as Marshall Levine, 72, and said he was found dead in his office, which indicated he was a “life coach,” Sgt. Hoster said.

Sergeant Lewis of the Phoenix Police described the suspect in Dr. Pitt’s killing as a bald, white male wearing a dark-colored hat with a short brim, “kind of like a fedora.”

He said that the police had been receiving “continual” tips from the community, but that no arrests have been made. Late on Saturday, the authorities announced that the potential reward for tips leading to an arrest and conviction in the homicides had been increased to $21,000.

Sergeant Lewis said he could not provide details about how the two crimes were connected, or whether the same person was suspected of both crimes. Sergeant Hoster said that although the department believes that the homicides are related, he could not offer any details about the suspect or suspects. He also said the police had not determined whether there was a connection between the paralegals’ law firm and Dr. Pitt and his practice.

Dr. Pitt and his firm, Steven Pitt & Associates, frequently consulted with the Phoenix Police Department, Sergeant Lewis said, most notably in the recent case involving the so-called serial street shooter, in which a suspect is in jail awaiting trial.