Whitney Houston's sister-in-law said she feared that drugs would end the singer's life.
In a partial transcript of an interview with Oprah Winfrey scheduled to air on Sunday, Patricia Houston said she would be "kidding herself" to say otherwise.
Patricia Houston, who was her sister-in-law's manager, was asked if she thought drugs would end up "taking" Whitney Houston. The "handwriting was kind of on the wall", she replied.
The pop star was changing how she lived, Patricia Houston said, and "it wasn't about substance abuse or anything like that relative to the ... latter days or anything like that.
"It was just more of a lifestyle. I was afraid for other things," Patricia Houston said. "I saw her chasing a dream, you know, looking for love in all the wrong places."
Bobbi Kristina, Whitney Houston's daughter with singer Bobby Brown, was also interviewed for the episode of Oprah's Next Chapter airing on Sunday on Winfrey's OWN channel.
The 19-year-old discusses how she wants her mother to be remembered, OWN said.
Houston, 48, was found underwater in a Beverly Hills hotel room bath on the eve of the Grammy Awards.
Investigators found several bottles of prescription medication in the room, and tests were being conducted to determine the cause of her death on February 11.
The pop star, whose hits included I Will Always Love You, had a history of substance abuse.