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 Tuesday, Reuters reports. The investigation could ultimately lead Melissa Rivers to file a 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. Rubinowitz declined to comment further or say if Melissa Rivers intended to file a lawsuit. Joan Rivers, 81, died in a hospital on Sept. 4, a week after she stopped breathing during an examination of the back of her throat and vocal cords at Manhattan's Yorkville Endoscopy.