Melissa Rivers, the daughter of comedian Joan Rivers, has hired a New York law firm to investigate the circumstances behind her mother’s death from a complication during an outpatient throat procedure, the firm said.

The investigation could ultimately lead Melissa Rivers to file a civil lawsuit against the clinic where her mother was treated.

“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 in a statement.

Rivers, 81, died in a hospital on September 4, a week after she stopped breathing during an examination of the back of her throat and vocal cords at Manhattan’s Yorkville Endoscopy.

New York’s medical examiner determined the brash comedian died from anoxic encephalopathy, a condition caused when brain tissue is deprived of oxygen and there is brain damage. Following Rivers’s death, the State Health Department launched an investigation into the clinic where Rivers was treated.

Melissa Rivers co-hosted cable network E!’s series Fashion Police with her mother before her death.