O’Connor, 49, recently performed in Chicago, taking the stage at Metro back on March 4 with Sons of the Silent Age. The performance, at a David Bowie tribute concert, included Sinead’s renditions of the Bowie classics “Sorrow” and “Life on Mars.”
Metro’s owner Joe Shanahan tells PEOPLE O’Connor “was in totally great spirits” during the March 4 set.
“She was in fine form – absolutely fine form – and her voice was in even better form,” says Shanahan. “She was there with a cigarette in one hand and a cup of coffee in the other. She was the surprise guest and she walked out and just brought the house down, hitting every single note.”
On Monday, O’Connor was found safe after being reported missing by Police Sgt. Michael Robinson of the Wilmette Police Department. Robinson sent out a check-for-well-being alert after a caller told authorities that O’Connor didn’t return from an early morning bike ride in Wilmette, a suburb of Chicago, Illinois, on Sunday, authorities told PEOPLE in a statement. Chicago’s WGN reported O’Connor was located at a hotel and was taken to the hospital.
While he couldn’t comment on O’Connor’s disappearance, Shanahan did call the short-lived search for the singer “a horrible thing,” noting “there’s no question we all went her to be safe.”