PHOENIX - A fourth professional found fatally shot in a three-day span has been identified by Arizona detectives as a 72-year-old counsellor and life coach, but authorities were not immediately linking his death to that of the other three.

Police in the Phoenix suburb of Scottsdale said Sunday that Marshall Levine was found shot inside an office building shortly after midnight Saturday. The Arizona Republic reported Levine worked as a hypnotherapist and life coach. He also provided marriage and divorce counselling.

On Thursday, Dr. Steven Pitt, a prominent forensic psychiatrist who assisted in high-profile murder cases including the JonBenet Ramsey mystery in Colorado, and a notorious Phoenix serial killer investigation, was found dead near Scottsdale. Witnesses reported hearing a loud argument and gunfire outside Pitt's office.

Police said the killings Friday of paralegals Veleria Sharp, 48, and Laura Anderson, 49, were related to the Pitt shooting, but were still trying to determine exactly what linked the three victims.

"We don't know the relationships or the connections," said Sgt. Ben Hoster.

How, or if, Levine's death also had ties to the killings of the two women and Pitt was still being investigated, Scottsdale police told The Republic.

Phoenix police say Pitt's killer was described as a bald man wearing a dark-colored hat with a short brim. Police released a sketch of the suspect in the three killings.

Sharp and Anderson were shot Friday inside a law office. Police say one of the women managed to walk to an intersection to seek help despite a gunshot wound to her head. She was taken to a hospital where she died.

Officers followed a blood trail back to the office and found the other woman. She was pronounced dead at the scene.

Hoster said there was no indication that family members of the victims were in danger.

"We're asking the public to remain vigilant and to call us if they notice anything out of the ordinary," Hoster said.

In the Levine case, Scottsdale police received a call Saturday about a man found fatally shot inside an office. Hoster did not identify the caller but said the person knew the victim.

The killing occurred in an office park that houses mostly therapists and counsellors.

Pitt, 59, assisted in the investigation of the 1996 death of 6-year-old JonBenet Ramsey, who was found dead at her home in Boulder, Colorado.

A decade later, he helped Phoenix police in the Baseline Killer investigation as they sought a man who was later convicted of killing nine people.

The website of Burt/Feldman/Grenier, the law firm that employed Sharp and Anderson, says it practices divorce, child support and other aspects of family law litigation and mediation.