Police escort hospital staff members and others away from a medical office building in Reno, Nev., on Tuesday, Dec. 17, 2013. A suicidal gunman killed one person and critically wounded two others before turning the gun on himself on the grounds of the Renown Regional Medical Center Tuesday. (AP Photo/Scott Sonner).

RENO, Nev. - Police confirmed the Northern California man who killed one doctor and wounded another last week at a Nevada urologist's office was a patient at the facility, and detectives are "actively looking into" his involvement in an Internet chat room where he reportedly complained about complications from a 2010 vasectomy, a city spokeswoman said Tuesday.

Alan Oliver Frazier, 51, an unemployed former power plant worker, made it clear in a suicide note that he planned the attack and that his focus was on the physicians at Urology Nevada, on the third floor of a Reno medical building, police said.

City spokeswoman Sharon Spangler confirmed investigators are interviewing a former fiancee of Frazier's who told The Associated Press he took medication for depression when they were together in the mid-1990s. They're also talking to a neighbour who says Frazier told him the day of the shooting that he was leaving and not coming back.

Police are releasing no information on whether the victims treated Frazier, and they have not yet established a motive, Spangler said. She said they are still reviewing his medical history and have made no determination as to whether he had a history of mental illness or had been suicidal in the past.

However, she confirmed detectives are in contact with the ex-fiancee, who told the AP he was a different person when he didn't take his medication for depression and was suicidal at least once during the 18 months they were together.

"We are aware, and we are interviewing her," Spangler said in an email to the AP. She also acknowledged investigators talked to the neighbour, Mike Hawthorne, who told the Reno Gazette-Journal that Frazier said the day of the shooting he wouldn't be back.

Reno Police Lt. William Rulla said authorities were aware that Frazier claimed he was "having adverse symptoms" from his surgery. He said they were in the process of securing Frazier's full medical records to determine the nature of the operation and his claims.

Citing a neighbour, the Gazette-Journal first reported that Frazier sometimes ranted in a Yahoo group about vasectomy pain that he was still suffering more than two years after what he claimed was a botched surgery.

Witnesses told investigators that Frazier said during the attack that he was looking for physicians, not patients.

Frazier entered the third-floor office on the afternoon of Dec. 17 with a shotgun and used it to kill Dr. Charles G. Gholdoian, 46, president of Urology Nevada. He also critically wounded Dr. Christine Lajeunesse and seriously injured Shantae Spears, who was accompanying a relative on an office visit.

News from © The Associated Press, 2013