Melissa Rivers Hires an Attorney to Investigate Her Mother's Death

— -- Joan Rivers' family wants answers.

The comedian's daughter, Melissa Rivers, has retained attorneys just weeks after her mother died suddenly at age of 81 on Sept. 4 during a medical procedure.

“In order to fully determine all of 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 Runbinowitz, a lawyer for the law firm of Gair, Gair, Conason, Steigman, Mackauf, Bloom & Rubinowitz, told ABC News in a statement.

Earlier this month, the New York City medical examiner said that Joan Rivers died of low blood oxygen while undergoing a procedure to treat voice changes and acid reflux. The "Fashion Police" co-host lacked sufficient oxygen to her brain for an extended period of time, which caused brain damage. Her heart had stopped after she was sedated with propofol.

Though a representative for the medical examiner's office told ABC News on Oct. 16 that it found no obvious medical error and ruled Rivers' death a "therapeutic complication," one day later, the clinic where she was treated, Yorkville Endoscopy, was found deficient by the New York State Health Department. During a routine investigation into the clinic, the department said it found lapses in four categories required for accreditation: governing body and management, surgical services, medical staff and patient rights.

Yorkville Endoscopy's accreditation will be terminated on Jan. 7, unless it can prove it has corrected the deficiencies, which a representative for the clinic said it will do.

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