The bodies recovered from a nursing home and hospital after Hurricane Katrina were so decomposed they may not yield any evidence for prosecuting crimes, the coroner overseeing the autopsies says.

Louisiana's attorney general charged the owners of a flooded-out nursing home in Chalmette with negligent homicide in mid-September after 34 bodies were discovered. He has also subpoenaed 73 people in an investigation into rumors that patients were put out of their misery at New Orleans' flooded-out Memorial Medical Center (search), where 40 people were found dead.

But Orleans Parish Coroner Frank Minyard (search), who is overseeing autopsies for the state, said this week that the bodies from the two institutions were so decomposed he listed the cause of death merely as "Katrina-related."

"There is no physical evidence from the autopsy that these people were murdered or euthanized," Minyard said. "If they did not have a knife sticking in them or a bullet in the body, it's hard pinpoint an exact cause."

He was still waiting for toxicology reports but said unless those show abnormal levels of morphine or another drug, those tests will not help.

Kris Wartelle, a spokeswoman for Attorney General Charles Foti (search), said the findings will not deter prosecutors.

"I know what our investigators found when they went down there. What he's saying does not change anything we're doing," she said.

Jim Cobb, an attorney for the nursing home owners, said the lack of autopsy evidence will make it difficult to prove the charges against his clients.