New Orleans grand jury moving in on Memorial Medical Center doctor

Disturbing news from CNN out of New Orleans:

(CNN) -- Two nurses accused in the post-Katrina deaths of four patients at New Orleans' Memorial Medical Center have been offered immunity to testify before a special grand jury, sources close to the investigation tell CNN.

Sources also told CNN the grand jury has been told as many as nine patients may have died after being administered what Louisiana's attorney general called a "lethal cocktail" of medications by hospital staff.

Family members said staffers used the drugs to kill patients so caregivers could flee appalling conditions inside the hospital after the storm.

Dr. Anna Pou and nurses Cheri Landry and Lori Budo were arrested in July 2006 after a 10-month investigation. Louisiana Attorney General Charles C. Foti charged them with second-degree murder.

Sources close to the investigation told CNN the two nurses are expected to testify before the grand jury in the next two weeks, which could signal a possible wrapping up of the case. It could also signal the main target of the investigation is Pou, a physician who was under contract with Memorial Medical Center when Katrina struck.

It's extremely important not to rush to judgment in this case. The report says "Family members said," and we don't know what the nurses are going to say when they testify. The offer of immunity is no doubt a worrisome turn of events for Dr. Pou, because the offer wouldn't have been made unless the DA thought they had something to give in exchange. But the last I heard (in her interview on "60 Minutes"), Dr. Pou persuasively denied that she killed patients at Memorial during Katrina. (Thanks to Dr. Mo Bernstein at USC for alerting me to this story.)