Offical Investigation: JOAN RIVERS doctors “failed to identify deteriorating vital signs and provide timely intervention” when she died.

According to an investigation held by the New York Department of Health and Human Services, that Rivers' manner of death was determined to be "therapeutic complication" death resulting from a "predictable complication of medical therapy," the medical examiner’s office said in a statement.

Yorkville Endoscopy’s violations include: not obtaining the patient's consent for a procedure, mistakes in administering the anesthesia Propofol, failing to take Rivers' weight, allowing an unauthorized doctor to perform a procedure and violating the patient's privacy by taking a cell phone photograph during surgery.

As The ENQUIRER previously reported Rivers, 81, was undergoing a laryngoscopy and an upper gastrointestinal endoscopy when she went into hypoxic arrest – a lack of oxygen to the brain.

Rivers was rushed to a hospital where she died Sept. 4 after being removed from life support.

Joan’s daughter Melissa hired the New York personal injury law firm of Gair, Gair, Conason, Steigman, Mackauf, Bloom & Rubinowitz to investigate.

Her lawyers issued a statement on her behalf:

"Our client, Melissa Rivers, is terribly disappointed to learn of the multiple failings on the part of medical personnel and the clinic as evidenced by the CMS report., Ms. Rivers is outraged by the misconduct and mismanagement now shown to have occurred before, during and after the procedure…"