gaps, well, we can only speculate. >> what do you think, what could have happened to rivers during the relatively routine procedure a week ago? >> one thing we do know is this is a clinic that specialized in endoscopy. now there are certain procedures involving endoscopy where you actually sedate the patient, and you put them under some sort of anesthesia. it could be mild. it could be more than that. but whenever a patient undergoes answer these, yeah you depress other things as well, things like heart rate and breathing. that's why we monitor patients under anesthesia. now, do we know for a fact that this had anything to do with it? we really don't. it could be that this was completely unrelated to the procedure at hand. right now there's an investigation under way. the clinic has not been accused of any wrongdoing. and we will only find out more once we hear from this investigation. >> a lot to learn. so many unanswered questions. dan childs, managing editor from the medical unit. thank you. >> thank you. >> be sure to stay with abc news as more tributes to joan rivers come in. colleagues are remembering this icon later this half hour. now to the search for those