The man who opened fire at a Nevada hospital, killing a doctor and himself, left a suicide note at his home and claimed he had botched surgery three years before the rampage, police have said.
Police in Reno did not give a motive but the new details could give a fuller picture of why the urology clinic at the Renown Regional Medical Centre was targeted by Alan Frazier, 51 .
Two other people were wounded in the shooting on Tuesday.
Police say Frazier, of Plumas County, California, had surgery in 2010 and claimed to have suffered adverse symptoms.
It was not immediately clear if the unspecified operation was performed at Urology Nevada, the site of the shooting, or if either of the two doctors who were shot had been involved.