With the official cause of Whitney Houston's death now released -- accidental drowning due to atherosclerotic heart disease and cocaine use -- a new TMZ report says someone may have removed all traces of cocaine from Whitney's hotel room as a way to hide evidence.

The L.A. Coroner's Office said in their report Whitney used cocaine "immediately prior to her collapse." But investigators who arrived on scene found no traces of the white powder or any other illegal substance.

The official cause of Whitney Houston's death has been released by the L.A. Coroner's office, which cites accidental drowning, with cocaine use and heart disease as the main contributing factors.

Along with cocaine, "Extra" has learned other drugs where in Houston's system, including marijuana, Xanax, Flexiril (a muscle relaxant), and Benadryl, but they did not contribute to her death.

Whitney Houston's daughter, Bobbi Kristina Brown, doesn't really care what her grandmother, Cissy Houston, has to say about her burgeoning relationship with "adopted" brother, Nick Gordon.

Sources close to Bobbi Kristina told TMZ the 19-year-old finally confirmed to friends she and 22-year-old Gordon, who Whitney unofficially adopted 10 years ago, are indeed dating.

TMZ reported Cissy saw the video showing Bobbi and Nick holding hands and kissing on a lunch run in Atlanta this week -- and told a close friend, "What [Bobbi and Nick] are doing is incestuous."

But Bobbi disagrees, telling her friends she doesn't consider dating Gordon incest because he is not her blood brother.

A source said Bobbi "can't please everyone, so she is going to please herself by doing what she wants to do for once."

Whitney Houston's mother, Cissy Houston, is reportedly upset over granddaughter Bobbi Kristina's romantic involvement with Whitney's "adopted" son, Nick Gordon.

According to TMZ, the bereaved grandmother was less than thrilled to see video of Bobbi Kristina and Nick kissing and holding hands. Cissy told a close friend, "What they're doing is incestuous." Cissy believes Bobbi Kristina is going through a rough patch and feels Nick is taking advantage of her.

In the interview with Oprah Winfrey on Sunday, Whitney Houston's brother Gary and sister-in-law/manager Patricia gave new details of the day the singer died.

Oprah opened the broadcast by saying "members of the family told me she (Houston) was face down and naked" in the bathtub, and Patricia said Houston's assistant, Mary, discovered the singer's body.

Whitney Houston's 19-year-old daughter, Bobbi Kristina Brown, sat down with Oprah Winfrey on Sunday on "Oprah's Next Chapter," where she opened up about her mother's death and how she's coping.

Here are some highlights:

The 90-minute television special also touched on Bobbi Kristina's father, Bobby Brown, who had a tumultuous marriage with Houston. While some have accused Brown of introducing Houston to drugs, Whitney's sister-in-law, Pat Houston, and brother Gary said that was untrue, and had warm words for Brown.