The New Haven Police Department and an organization that accredits hospitals are both conducting investigations into the Jan. 11 and Jan. 15 operating room deaths of two women at the Hospital of St. Raphael, officials at the hospital said Saturday.

Hospital administrators disclosed at a Jan 16. press conference that the two women died while undergoing the same routine heart procedure after they were mistakenly given an anesthetic instead of oxygen.

Police were unavailable to confirm the status of the investigation last night, but the hospital hoped authorities would “formally and completely” rule out the possibility of wrongful death when they visit the facility tomorrow.

The Joint Commission on the Accreditation of Healthcare Organizations will conduct a site visit in March. The organization accredited the hospital in March 2001.

Hospital officials have blamed the mix-up on a combination of equipment failure and human error. Apparently, an employee or employees plugged a machine that regulates oxygen flow into a receptacle that dispenses nitrous oxide because the flow regulator was missing an important “safety prong” that would have prevented such a mix-up.

Doris Herdman, 72, of Southington, died Jan. 11 while undergoing a diagnostic cardiac catheterization procedure. Joan Cannon, 68, of Wallingford, died four days later during the same operation, in which doctors use a flexible tube to inject dye into the heart to check for blockages.

The hospital also said Saturday that nitrous oxide is not used during any surgical procedures that are performed in the operating room where the patients died.

“Several people have asked why nitrous oxide would be available in a cardiac catheterization lab, when it’s not used during these procedures,” officials said in a statement. “In retrospect, we realize that access to nitrous oxide should and could have been removed from the lab.”

Because the deaths involve the apparent malfunction of a medical device, the federal Food and Drug Administration is conducting its own investigation.

The company that made the machine, Precision Medical Inc., of Northampton, Pa., did not returned repeated phone calls last week.

The Public Health Department of Connecticut is also investigating, and its representatives will return to the hospital this week.

Hospital officials said yesterday that they will not discipline any of the employees involved in the mistake.

“We have identified employees who had specific roles in the multiple processes and systems that broke down,” they said. “We continue to believe the human errors were unintentional.”

Because the hospital does not believe the employees are culpable, it did not release their names.