Updated

A patient who disappeared from her room at San Francisco's main hospital last month was identified Wednesday as the woman found dead in an emergency stairwell, horrified authorities said as they continued to investigate how she got there and died.

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San Francisco General Hospital Chief Medical Officer Todd May said officials were still awaiting confirmation of the woman's identity from the medical examiner's office. But he said the hospital had enough information to conclude the body discovered in the fourth-floor stairwell this week belonged to 57-year-old Lynne Spalding.

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"What happened at our hospital is horrible," a visibly emotional May said at a news conference. "We are here to take care of patients, to heal them, to keep them safe. This has shaken us to our core. Our staff is devastated."

The San Francisco Sheriff's Department provides security at the city-owned public hospital, which has more than 400 beds and serves about 100,000 patients a year.

Sheriff's officials do not yet know how long Spalding had been in the stairwell, which is part of a rarely used fire exit that has an alarm on it, is locked from the outside and exits onto hospital grounds, Assistant Sheriff Paul Miyamoto said.

She was admitted to San Francisco General Hospital for an infection on Sept. 19 and was reported missing from her room there two days later.

Miyamoto said a member of the hospital's engineering staff found Spalding on Tuesday — 17 days after she disappeared — while conducting a routine quarterly check.

"All of us are committed to learning what happened and insuring it never happens again," Miyamoto said.

David Perry, a friend of Spalding's who is acting as a spokesman for her family, called the news a "nightmare" and said city officials have a lot of explaining to do.

Spalding's relatives and friends spent days "scouring the streets of San Francisco with flyers because we were under the assumption that San Francisco General had been searched and Lynne was not here," Perry said.

"Lynne Spalding died alone, in the stairwell, at one of the finest medical institutions in this country," he said. "I hear that the San Francisco Sheriff's Department initiated a search. Well, evidently it wasn't a very good one. I think there are a lot of questions to be asked."

Perry said Spalding had worked in the travel industry and she lived not far from the hospital with her 23-year-old daughter. In the days before she entered the hospital, Spalding had lost weight and appeared disoriented and weak, he said.

Her daughter and boyfriend took her to the hospital to be checked out and were told she needed to be admitted for treatment of a possible urinary tract infection, Perry said.

"They were worried about her. She looked sick, and she was acting sick," he said.

During the two nights she spent at San Francisco General, Spalding seemed to be getting better and her condition was upgraded to fair, May said. Nurses were checking on her every 15 minutes, and she disappeared in the brief time between those visits, May said.

Spalding's family filed a missing person's report with police, who have been investigating her disappearance.

The Sheriff's Department is conducting an internal investigation of its security measures at the hospital.