Melissa Rivers, daughter of the late comedienne Joan Rivers, hired a New York law firm to investigate the circumstances surrounding her mother's death, Reuters reported.

Rivers, 81, was being examined for voice changes and possible acid reflux at the Yorkville Endoscopy clinic in Manhattan when she went into cardiac arrest. She was rushed to Mount Sinai Hospital and put on life support, but passed away Sept. 4.

The New York Medical Examiner stated that Rivers died from anoxic encephalopathy or brain damage due to deprivation of oxygen and the death was ruled as a medical complication of her check-up.

While official statements have been made, the exact nature of Rivers' death and the supposed complications still leave a lot of questions unanswered, according to The New York Times.

The situation leads to questions in regards to errors of omission concerning medical reports, errors in clinical judgment or management of patients or the possibility of a missed diagnosis, according to the the medical examiner's office.

The investigation on Rivers' death could lead to her daughter filing a civil lawsuit against the clinic where her mother was treated, according to ABC News.

"In order to fully determine the facts and circumstances surrounding the death of Joan Rivers, we confirm that our firm has been engaged by Melissa Rivers and her family," Ben Rubinowitz, a partner at Gair, Gair, Conason, Steigman, Mackauf, Bloom & Rubinowitz said.

Rubinowitz declined to comment on whether or not there were plans to file a lawsuit.

A representative for the medical examiner's office said that it found no medical errors concerning River's death, but the New York State Health Department found other areas of concern concerning the Yorkville Endoscopy clinic.

The New York State Health Department found other areas of concern concerning the Yorkville Endoscopy clinic. The department said it found lapses in categories required for accreditation such as governing body and management, surgical services, medical staff and patient rights. 

"The center has been working collaboratively with appropriate government regulatory agencies to ensure complete compliance with all regulations," a spokesperson for the clinic said. "The center remains open and will continue to collaborate with all accreditation and government regulatory agencies to ensure quality care."