Prosecutors filed criminal charges against a major hospital company accusing it of dumping a homeless patient suffering from dementia on the city's crime-plagued Skid Row, the city attorney said Thursday.

"They have violated every ethical obligation under which they operate and they have also broken the law," City Attorney Rocky Delgadillo said at a news conference announcing the charges.

Police have long suspected that medical centers and outside law enforcement agencies were using the neighborhood as a dumping ground for the homeless. Skid Row already has one of the nation's largest concentrations of homeless people, in part because of its cluster of shelters and services to help them.

In the case against Kaiser, a 63-year-old patient from Kaiser Permanente's Bellflower hospital was recorded on surveillance video in March wandering Skid Row in a hospital gown.

She had continuing, untreated serious health problems when she was found by a homeless shelter's staff, Delgadillo said.

"Kaiser Foundation Hospitals, part of Kaiser Permanente, the largest HMO in the nation, will be held accountable for violating state law, its commitment to its patients, its obligations under the Hippocratic oath, and perhaps most importantly, principals of common decency," Delgadillo said.

The legal action was the first in Los Angeles and experts said it appeared to be unprecedented nationally. Delgadillo said the charges and a civil lawsuit against Kaiser Permanente are a first step in holding hospitals accountable.

The Bellflower hospital is among 10 Los Angeles-area hospitals under investigation for allegedly discharging homeless patients onto the streets instead of into the custody of a relative or shelter.

Delgadillo filed criminal charges of false imprisonment and dependent adult endangerment naming both Kaiser Foundation Hospitals and Kaiser Health Plan Inc.

A civil law enforcement claim under the state business and professions code involving treatment of patients and laws on discharging patients names Permanente Medical Group, Delgadillo said.

Diana Bonta, vice president of public affairs for Kaiser Southern California, told the Los Angeles Times that Kaiser has taken steps to see that no more of its patients are left on Skid Row.

"As soon as we heard about it (the case in March), we said, 'this is not how we do business.' And we apologized," she said.