Dionne Warwick on What She Thinks Killed Whitney

Dionne Warwick is opening up to ET about the death of her cousin Whitney Houston and reveals what she thinks killed the pop superstar.

When asked what she expects to hear when authorities issue a final cause of death for Houston following the results of toxicology tests, Warwick tells ET, "You know, in all honesty, I think she had a heart attack, that's what I think happened to her." When asked about possible drug use playing a role, Warwick added, " I don't know if it's that or not. I think her heart just gave out."

Dionne Warwick's Last Conversation with Whitney

Warwick also spoke about the feelings she had while accompanying Houston's body aboard the plane that transported the Grammy winner back to her native New Jersey. "It was a combination of things, stories, laughter, tears. All the emotions that you feel when somebody very near to you passes."

Video: How Dionne Warwick Is Coping With Her Loss

We caught up with Warwick as she worked in the studio on a new album, which remains untitled at this point. However, Warwick is calling it her "50th Anniversary" celebration album that will include some new original songs written for her by Burt Bacharach.

Video: Bobbi Kristina Recounts Her Last Day with Whitney

Tune in to ET tonight for more of Dionne's exclusive interview about Whitney Houston.