Reno medical center shooter identified NEW: Shooter left a letter indicating his intent NEW: He had had surgery in 2010 and claimed he was having adverse symptoms City official identifies third victim as Dr. Christine Lajeunesse (CNN) -- The gunman in the Reno, Nevada-area medical center shooting that left one person dead has been identified as longtime Plumas County resident Alan Frazier, 51, Sheriff Greg Hagwood said Thursday. Frazier had no serious run-ins with law enforcement before Tuesday's shooting, which also left two victims injured and Frazier dead from a self-inflicted gunshot wound. Without elaborating, police said Wednesday that the attack did not appear random. Dr. Charles Gholdoian, 46, was killed, and patient Shawntae Spears, 20, was wounded, Reno Deputy Police Chief Mac Venzon said at a news conference. Dr. Christine Lajeunesse is in critical condition, but conscious, a spokeswoman for the city told CNN on Wednesday. Spears and Lajeunesse suffered single gunshot wounds. Spears also is in critical condition at Renown Regional Medical Center. The investigation, which includes interviews with 29 witnesses, indicates Frazier walked past the front desk to a patient exam room area and fired five rounds from his 12-gauge shotgun. Police don't have a motive, but according to a statement from the City of Reno that summarized comments from Reno police Lt. William Rulla, the shooter's focus might have been on physicians at the office. He had had surgery in 2010 and claimed he was having adverse symptoms because of it, Rulla said. As part of their investigation, detectives served a search warrant at Frazier's home. They discovered a letter there that indicated his intent, as well as other firearms and notes suggesting the shooting was to be his final act, the lieutenant said. CNN's Mayra Cuevas, Eliott C. McLaughlin, Chandler Friedman and Steve Almasy contributed to this report.