Tonight, new information on Jackson's history with potent sleep drugs -- 360 M.D. Sanjay Gupta has been on the trail of a doctor who we've learned worked for Jackson on tour in the late 1990s, an anesthesiologist himself with a checkered medical past. Sanjay what have you learned?
DR. SANJAY GUPTA, CNN CHIEF MEDICAL CORRESPONDENT: Well, I'll tell you. We know several things now. Sources close to Michael Jackson tell us that during the "History" tour back in '96 and '97 Jackson was actually traveling with what looked like a mini clinic, including an IV pole, drips and what looked like a rack with lights and monitors and such.
Sources who had the opportunity to see Jackson at various points during the tour say Jackson was traveling with at least two doctors and one of whom was anesthesiologist Dr. Neil Ratner.
Now, one source said he asked Ratner about all this elaborate equipment, and Ratner said he was there because Michael simply couldn't sleep. Now Ratner went on to say, according to the source, "I take him down at night" -- referring to Jackson -- "and I bring him back up in the morning."
Now, a source said Michael Jackson often appeared groggy. And when the source asked Jackson about all of this equipment, he just said he needed sleep. So, it was pretty remarkable, Anderson, to just hear that so clearly.
COOPER: Well Sanjay, I mean, over the past couple of nights we've talked to each other about how dangerous powerful anesthetics can be. Do we know anything about precautions taken to protect Jackson on this tour?
GUPTA: Yes, we do. Sources say that Ratner would keep the equipment in his hotel room, which would be next to Jackson's. And he would use that for monitoring Jackson's vital signs when he was asleep, or under, as the source put it.
Now, there was a "Vanity Fair" article that said a former business associate of Jackson's said the singer had a quote, "sleep disorder," and then Ratner confirmed that to us today on the phone.
But I really want to talk to him some more, so we tracked him down, Anderson, today at the Woodstock, New York, where he now lives with his wife. Here's what he had to say.
(BEGIN VIDEO CLIP)
GUPTA (on camera): We've come here because your name was obviously associated with Michael Jackson. And people said that there was a question of whether or not you gave anesthesia to him while he was on tour. And we just wanted to come to the source, you, and hear and find out if that had happened.
DR. NEIL RATNER, FORMER PHYSICIAN OF MICHAEL JACKSON'S: I'm very upset. I'm distraught. Michael was a good person.
I can't talk about it right now. It's really something I don't want to talk about right now. I've lost a friend and I feel very badly about that.
GUPTA: There were two people, and I just want to allow you to respond to this. And you can or you don't have to. But I think it's important that you hear this. We have a couple of different sources have said they would see IV equipment, what sounded like probably pumps, they described as sort of an audio rack sort of looking thing in a hotel room with Michael. And they made it sound like that was your stuff. Are they wrong? I was really...
RATNER: I don't want to talk about this topic at all now. I really have nothing to say about it right now. You know? The man hasn't had a funeral, and the man hasn't been buried. It's inappropriate. I don't want to talk about it right now. And I appreciate it if we could end this now.
(END VIDEO CLIP)
GUPTA: So, who is Dr. Neil Ratner? Well, he's a board-certified doctor who, as we mentioned, served as one of Jackson's doctors on that "History" tour that spanned '96-'97; over 80 performances on that tour.
Now, Ratner was actually stripped of his medical license for three years back in 2002 after being found guilty of insurance fraud -- Anderson.
COOPER: So, back to the hotel rooms, the "History" tour. Did Ratner or your sources say anything about seeing -- there's been talk about this drug Diprivan or Propofol in the last couple days because of this registered nurse who said that Jackson asked her for that three months ago. And has the sources mention anything about that?
GUPTA: Well, there's no specific mention of those -- medication Propofol, also know as Diprivan, no specific medication. But it's worth noting that, now we're talking back in '97. At that time at least Propofol wasn't nearly as commonly used as it is today. But there weren't specific drugs mentioned, just that equipment -- Anderson.
COOPER: Is it odd to you as a medical doctor to have an anesthesiologist with somebody on a tour?
GUPTA: Completely odd. No question, very odd, and to have all that equipment as well. I've never heard of such a thing, to have that equipment outside some sort of medical setting. So you know, I'm hearing things that frankly I've never heard of before as a doctor.
COOPER: All right. Sanjay, obviously a lot still we don't know. And just to be clear, we do not know what, if any drugs, Michael Jackson was taking for insomnia or for any other reason. And we won't know until the toxicology reports are made public.
I'll keep looking at the facts.