Melissa Rivers opens up about her mother's death in an upcoming interview with Today co-anchor Matt Lauer due to air Monday, May 4.
In a snippet of the interview released by NBC, Melissa reminisces on the day her mother died and the events leading up to it.

"I just couldn't believe what I was seeing," she said about what went through her mind as she entered the hospital where her mother was being held. "It--it becomes every surreal."

Joan Rivers died at 81 a week after complications for a minor surgery prompted cardiac arrest. Melissa, 47, filed a lawsuit against the clinic where the complication occurred, which led to an investigation that produced evidence of malpractice.

"In my opinion, it was 100 percent preventable," Rivers said of her mother's death.

The full interview with Melissa Rivers is scheduled to air Monday, May 4 on the Today show.