More arrests are likely as authorities investigate at least 140 patient deaths at nursing homes and hospitals during and after Hurricane Katrina (search), including allegations that some patients may have been euthanized, the Louisiana attorney general's office said Friday.

Six hospitals and 13 nursing homes in Louisiana are under investigation.

The investigations were wide-ranging, looking into whether patients were abandoned, evacuated improperly, or euthanized to spare them further suffering, said attorney general's spokeswoman Kris Wartelle.

The majority of the agency's Medicaid Fraud Control Unit — 18 investigators and four lawyers — have been assigned to the cases, Wartelle said.

She released no further details on the investigations.

Only two people have been arrested so far. The husband-and-wife owners of a St. Bernard Parish (search) nursing home were charged Sept. 14 with negligent homicide in the deaths of 34 people who were in the facility as flood waters rose.

A lawyer for the owners, Salvador and Mable Mangano, said the couple decided it was safer to keep the frail patients in the home rather than risk further health problems with a disruptive evacuation. He says the couple is innocent.

The attorney general's office previously confirmed it had seized records and other material from Memorial Medical Center in New Orleans (search), where 34 patients died after the hospital was cut off by flood waters.