Dr. Conrad Murray "was the one that was administering [propofol]," she says in a new interview with Robin Roberts on ABC News, referring to the powerful anesthetic that killed the star. "I think he is responsible."
Murray, who has admitted administering propofol to the singer, has consistently denied any wrongdoing.
Janet Jackson, 43, also describes how she found out her brother had been rushed to the hospital – and how she later learned the shocking news that he'd passed away.
"I was at my house in New York. You know, another day. Another morning. And I get a call ... [My assistant] said, 'Your brother's been taken to the hospital. It's on CNN right now,'" Janet tells Roberts. "I called everyone's … There's a line busy or someone wasn't picking up. I spoke to mother. I spoke to Tito. I spoke to my nephew Austin. I spoke to my sister La Toya.
"I told them to call me when they got to the hospital. And I remember thinking nobody's calling me back, so I tried calling again, and that's how I found out that he was no longer ... I couldn't believe it," she said. "It just didn't ring true to me. It felt like a dream."
Even now, she says, "It's still so difficult for me to believe. It's, you know, you have to accept what is. But it's hard. You have to move on with your life. You have to accept what is and I understand that."
As for how she's coping she says, "It's been a tough year … And a day doesn't go by that I don't think about him."
Roberts' interview with Janet Jackson will air Wed., Nov. 18 at 10 p.m.