Phoenix police are investigating after well-known forensic psychiatrist Dr. Steven Pitt was shot and killed outside his office Thursday night.

The shooting was reported outside Pitt's office near N. Scottsdale Road and E. Greenway Parkway at about 5:30 p.m., according to Sgt. Vince Lewis.

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Pitt's shooting has now been linked by police to the homicides of two paralegals in Scottsdale Friday. And police are investigating if a fourth homicide is related.

[RELATED: 4th homicide confirmed in Scottsdale, may be connected to recent murders]

Witnesses told police they reported hearing a loud verbal argument outside the office, followed by gunshots. Pitt, 59, was found critically wounded and was pronounced dead on scene.

Police are still searching for the suspect. He is described as a white male, bald and wearing a dark colored hat with a short brim. Phoenix police released a sketch of the suspect Friday morning.

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[RELATED: DOUBLE HOMICIDE: Two women shot and killed at south Scottsdale law office]

Pitt served as a consultant to police and prosecutors in JonBenet Ramsey’s homicide investigation. He was an adviser to the Jefferson County District Attorney’s Office following the mass shooting at Columbine High School, and he served on the police task force in the Valley’s Baseline Killer case.

[READ MORE: Forensic scientist looks inside minds of alleged serial killers]

On Saturday, Scottsdale police determined that the shooting death of Pitt was connected to a double homicide of two female paralegals at a law office.

Anyone with information about this crime is asked to call Silent Witness at 480-WITNESS, or for Spanish speakers, call 480-TESTIGO. Callers can remain anonymous and may earn an award of up to $1,000.

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