Despite their best efforts, Janet says Michael didn't change. "He was very much still in denial," she says.
During one failed intervention, Janet says she had to walk away. "I couldn't take it. I was just so overwhelmed with emotion, and I actually had to walk out of the room. It was just too much for me to handle."
Watch Janet discuss her family's attempts to help Michael.
"Do you think he was depressed?" Oprah asks.
"There's a part of you that has to be in order to do that, to let yourself go to that place, to get that down to need something to numb the pain," Janet says.
In February 2010, Los Angeles prosecutors charged Dr. Conrad Murray with involuntary manslaughter in Michael's death. They claim he administered a lethal dose of Propofol, the powerful operating room anesthetic that killed the music legend.
Janet says she blames Dr. Murray for her brother's death. "He [was] the one administering the drug, from what I know," she says.