Actress-comedian Joan Rivers stopped breathing and suffered from serious complications while undergoing a minor operation on her throat at an outpatient clinic in Yorkville, Manhattan in late August. She never woke from a medically induced coma and eventually died on Sept. 4.

Now, a federal report has revealed that the doctors who performed Rivers' procedure made several errors that could have led to her death.

On Nov. 10, the New York Department of Health released a report that says the Manhattan clinic, Yorkville Endoscopy, did not notice that Rivers' vital signs were deteriorating at least 15 minutes prior to her cardiac arrest, which eventually led to her death several days later.

The report said that although Rivers' blood pressure and pulse had decreased rapidly between 9:12 a.m. and 9:26 a.m. during her operation, cardiopulmonary resuscitation had only been done at 9:28 a.m.

"The physicians in charge of the care of the patient failed to identify deteriorating vital signs and provide timely intervention during the procedure," reported the investigators from the federal Centers for Medicare and Medicaid Services.

Investigations have found that the clinic's anesthesiologist later made changes to the medical records to say that the actress was given 120 milligrams of the sedation drug Propofol, saying that the original entry that says the amount given was 300 milligrams was a mistake caused by wrongfully double-clicking the clinic's automated entry system.

Investigators have also cited the taking of cellphone photos of Rivers and her ear, nose and throat doctor Gwen Korovin while the patient was sedated and without her consent. Lawrence Cohen, the medical director of the clinic at the time and the person who took the photos, told people in the room that Rivers may want to see the photos in the recovery room, although it was a violation of the clinic's cellphone policy.

It also turned out that Korovin was allowed to perform procedures on Rivers regardless that she was not a member of the clinic's staff and that Rivers did not give consent to these procedures.

The lawyers of Rivers' daughter, Melissa, said that their client is very disappointed after learning how the clinic and the medical personnel screwed up.

"As any of us would be, Ms. Rivers is outraged by the misconduct and mismanagement now shown to have occurred before, during and after the procedure (on her mother)," the lawyers said.