Joan Rivers' Friend Deborah Norville Shares Details of the Comedian's Last Days

— -- Fans were devastated by the death of Joan Rivers on Sept. 4. To her close friends and family, the loss is immeasurable.

"There was every reason to hope that this would be a different outcome because Joan was so vibrant because Joan’s mind was so sharp," Deborah Norville told ABC News in an interview that will air on a special edition of "20/20," "Joan Rivers: Living for the Laugh," tonight at 10 p.m. ET. "This was an 81-year-old woman who was running circles around people a third her age."

Norville knew Rivers better than most. The two became close in 1991, when the former "Today" host, who had previously been eviscerated in Rivers' comedy routine, made an appearance on Rivers' show. After Norville was made to understand that Rivers hadn't meant to hurt her feelings, the two became friendly. When they found themselves at a weekend-long wedding together a year or two later, their bond was solidified. In the end, Norville was at Rivers' bedside during her last few days at the hospital.

"Joan’s friends were her other family -- the chosen family. And [her daughter] Melissa made sure that not only were we able to be there for her but that we were able to be there for Joan. Because she knew how important that was for Joan’s friends to be able to be there for her," the "Inside Edition" anchor said. "Just to talk about the stupid stuff of life and just make jokes, because she wouldn’t want you to be maudlin. That would be horrible. She would kick you off. And, you know, I half-thought about being maudlin just to see if she’d wail back and punch me or something."

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If only. On Aug. 28, a week before her death, Rivers suffered cardiac arrest after undergoing what Norville described as "a diagnostic procedure ... [to] see why her voice had gotten raspy." The New York Health Department has opened an investigation into the clinic to determine if it should be cited for violations. A source told ABC News on Sept. 4 that there was no suspicion of wrongdoing at that time.

"I personally am really grateful to the Health Department of New York for launching an investigation, and asking these questions so that that there will be answers," Norville said, "and so that Joan’s family is not in the position of having to wonder or of having to drive the process."

After it was clear that Rivers was in distress, she was rushed to Mt. Sinai hospital, where she arrived unconscious. Doctors kept the comedian sedated and put her on life support. On Sept. 3, she was moved from ICU to a private room, where she died the next day.

"At a certain point, it was clear that the Joan that we loved was not a Joan that we would get to be with again, and I was given the privilege of getting to say goodbye," Norville said. "There’s no doubt that Melissa made sure that Joan did not die in a setting that seemed coldly medical; that Joan’s final moments would be in a space where she was surrounded by beautiful flowers because she always had spectacular flowers in her home, lovely things, and the people she cared about -- and that’s exactly how she left. And that’s exactly how each of us, if we’re lucky, should get to slip from this world."

Now, Norville is standing by Melissa Rivers' side as she plans the funeral and braces for life without her mother. One thing to smile about, she added, was that Rivers would have loved the worldwide attention her death has garnered.

"As horrible as it is to have lost this unbelievable treasure, dang, she would love every bit of this publicity," Norville said. "[Our friend] said, 'Yeah, you know, the awful thing is the one person who would think this is fabulous isn’t here to enjoy it.' Joan would love this."