(CNN) -- A man suspected of opening fire at a Tennessee hospital Monday, killing one and wounding another before killing himself, had a history of mental health problems, police said Tuesday.
Investigators searching suspected shooter Abdo Ibssa's home found medicine for psychotic problems and a note indicating that Ibssa believed a doctor at the hospital had placed an electronic chip inside him during a 2001 appendectomy, Knoxville Police Chief Sterling Owen IV told reporters Tuesday.
"The suspect believed he was being tracked due to this chip," Owen said.
Owen said family members had committed Ibssa to a mental health facility in February, but it was not clear when he had been discharged.
Police said Ibssa shot three women outside the Parkwest Medical Center in Knoxville, Tennessee, Monday afternoon before shooting and killing himself.
Rachel Wattenbarger, 40, died from gunshot wounds.
The two survivors -- Ariane Guerin, 26, and Nancy Chancellor, 32 -- were taken to the trauma center at the University of Tennessee hospital. Owen said Tuesday that they were in stable condition.
When Ibssa showed up at the hospital Monday afternoon, he asked for the doctor who had apparently performed his appendectomy. He was told the doctor was not there, Owen said, and later opened fire outside the facility.
Owen said the .357 Magnum revolver used by the shooter was reported stolen from a residence in Knox County, Tennessee, in March.
Police searching Ibbsa's home also found a Beretta .22 handgun and a book called "The Official CIA Manual of Tracking and Deception," Owen said.