(CNN) The killings of three people this week in Arizona are thought to be related and authorities are investigating the death of a fourth person to see whether it is connected, Scottsdale Sgt. Ben Hoster said Saturday.

The victims include famed forensic psychiatrist Steven Pitt, who was involved in several high-profile cases, including the investigation into the death of child beauty queen JonBenét Ramsey in 1996. He was found shot dead in Phoenix on Thursday after witnesses heard a loud argument and gunshots, officials said.

The other victims were 48-year-old Veleria Sharp and 49-year-old Laura Anderson, two paralegals at a Scottsdale law firm who were killed Friday afternoon.

They also were shot, police said in a news release.

"We are in the middle of our investigations so I'm not going to talk about who's being investigated or what's happening," Hoster told reporters Saturday. "We're asking for help from the public."

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