CLEVELAND (AP) — Two adult brothers suspected of being involved in the fatal shooting of their physician father before turning guns on themselves during a SWAT standoff were reclusive, paranoid and likely mentally ill, a suburban Cleveland police chief said.

Authorities have said Richard Warn, 59, was found shot multiple times Aug. 9 by police officers at his home in the upscale suburb of Beachwood last week after his wife reported she couldn't get inside upon her return from a European vacation. Warn had flown with his wife to Newark, New Jersey, for an overseas connection but then decided not to travel because of motion sickness and drove home in a rental car.

A SWAT team accompanied detectives to a modest home in South Euclid that Warn had bought for his sons, 31-year-old Michael Warn and 29-year-old Mark Warn, in 2011 out of foreclosure. The SWAT team breached the front door of the home with an armored vehicle and was met by high-powered rifle fire that shattered the vehicle's ballistic glass window. The SWAT team returned fire and then waited 12 hours before going inside and finding the brothers dead from what a medical examiner has ruled to be self-inflicted gunshot wounds.

Beachwood Police Chief Gary Haba has said it's unclear whether one or both of the brothers killed their father.

South Euclid Police Chief Kevin Nietert told The Associated Press on Friday that he could only speculate why the Warn brothers would have wanted their father dead.

"In this case, we're going to struggle to get conclusive answers," Nietert said.

It appeared that the brothers relied on Richard Warn for financial support, Nietert said. They had no jobs, no apparent presence on social media, and drove an older model sedan their father bought for them.

A Beachwood police report from September 2015 describes Richard Warn's wife and the brothers' stepmother, calling 911 from a bathroom because she could hear voices inside the home. Police officers found the doors locked. Richard Warn soon arrived and said a car in the driveway belonged to his sons. The brothers told police they were looking for hats.

"Richard said that Michael and Mark were not to be at the house because they no longer lived there," the police report said.

Later that night, two officers returned to the home and listened to a voicemail Michael Warn had left for his father. Michael Warn said in the voicemail that he and his brothers' home was uninhabitable because of mold and that people do "crazy things" when they don't get enough sleep. He then warns his father that if he doesn't give him money, Jehovah might become upset and start burning things.

Nietert believes both men suffered from mental illness, although he said no records have been found to show whether they had been diagnosed or received treatment. A Cuyahoga County mental health agency called Mobile Crisis called South Euclid police in November 2015 asking to escort an outreach worker to the home. Nietert said it's unclear who called the agency or what the problem might have been, but nobody answered the door and nothing further was done.

South Euclid police reports show that Michael Warn called police a half-dozen times in 2014, mostly to complain about cars parked too close to his driveway.