ABC News(PHOENIX) — The individual who police believe murdered four people over several days in Arizona was found dead at a hotel early Monday morning, Phoenix police said.The adult male suspect — who authorities did not name — died from a self-inflicted gunshot wound, Phoenix Police spokesman Sgt. Vince Lewis said.Evidence links the suspect to four different killings in Phoenix and nearby Scottsdale, police said. Law enforcement sources told ABC News all four shootings used the same gun.Prominent forensic psychologist Steven Pitt was the first of four people to be killed, law enforcement officials told ABC News. Pitt, who consulted with law enforcement on a handful of prominent cases, including the JonBenet Ramsey murder and the Jodi Arias trial, was shot and killed outside his Phoenix office on Thursday night. An eyewitness said he heard Pitt loudly arguing with someone followed by gunshots, according to police.Law enforcement officials told ABC News on Sunday that this person is the only known eyewitness to any of the murders. The suspect was described by police as a white man wearing a black cap with a short brim.Scottsdale police had already connected the Friday afternoon killings of paralegals Veleria Sharp, 48, and Laura Anderson, 49, to the same suspect. The murder of Marshall Levine, who was killed just after midnight Saturday in Scottsdale, Arizona, has now been linked to the same gun used in all four murders, law enforcement officials said.The sources said the motive in the four killings remains unclear, but this is likely “family related.” Levine’s ex-wife, Carol Kleinman, told ABC News that Levine was a psychiatrist but was only licensed to practice in New Jersey.Since moving to Arizona, Kleinman said Levine worked as a life coach and hypnotherapist and dealt with clients who often “are angry.” Levine’s body was discovered by an acquaintance inside of his Scottsdale office in a neighborhood known as The Greens at Gainey Ranch — about 17 minutes from where the paralegals were shot.Law enforcement officials told ABC News on Sunday that one of the two paralegals actually crawled to a limo bus after being shot and alerted the driver, who called police. Police followed the trail of blood left by that woman to find the other, who was shot to death in a law office.“We are confident that both crime scenes are related,” police spokesman Lewis said Saturday of the shootings of Pitt and the two paralegals.Steven Pitt & Associates is headquartered in Phoenix but Pitt worked on a number of nationally known cases, including Ramsey’s murder. The murder of the 6-year-old beauty pageant competitor who was found dead in the basement of her family’s home in Boulder, Colorado, has never been solved. Pitt was brought on in February 1997 to help develop a psychological profile of Ramsey’s parents, according to multiple reports at the time.Pitt also consulted on cases including the Columbine High School massacre, Kobe Bryant’s sexual assault case and the Phoenix serial killer known as the “Baseline Killer,” who was sentenced to death for murdering nine people in 2005 and 2006.Copyright © 2018, ABC Radio. All rights reserved.