- Houston's sister-in-law says the late singer was "chasing a dream"
- She and Bobbi Kristina Brown, Houston's only child, speak to Oprah Winfrey
- Daughter says she can still hear her mother's voice and feel her spirit sometimes
- Houston, 48, died in her Beverly Hills hotel room last month
(CNN) -- Whitney Houston's only child opened up Sunday about her late mother in her first interview since the singer's death last month.
Bobbi Kristina Brown, 19, told Oprah Winfrey she can still hear her mother's voice sometimes and feel her spirit, urging her to "keep moving."
"She's always with me. I can always feel her," Brown said during the interview that aired on Winfrey's network, OWN.
On the same show, Winfrey also spoke to Houston's sister-in-law and friend, Patricia Houston, and her brother, Gary Houston.
Whitney Houston, 48, died February 11 in her room at the Beverly Hilton Hotel in Beverly Hills, California, the day before the music industry gathered for the Grammys in Los Angeles.
The famed singer won six Grammys and sold 170 million albums, singles and videos during her career. But in recent years, her struggles with drug addiction overshadowed her accomplishments.
When asked whether she feared drugs would one day take her friend, Patricia Houston told Winfrey she "would be kidding" to say otherwise. "The handwriting was kind of on the wall."
Recently, she said, she observed Houston "chasing a dream, looking for love in all the wrong places."
Houston was married to singer Bobby Brown from 1992 until 2007. Bobbi Kristina was born in 1993.
"I'm her daughter. I gotta keep moving. I gotta carry on her legacy. ... I still have a voice," Brown told Winfrey.
The grief comes in waves still, Brown said, and sometimes it doesn't seem real that her mother is gone.
"I'm getting through it. I'm doing as good as I possibly can," she said. "Just trying to keep going."
Sources close to the investigation into the singer's death told CNN on Friday that officials were looking to speak with her daughter before closing the case. They said it was unclear whether Bobbi Kristina would agree to be interviewed.
She was interviewed briefly by Beverly Hills police the day her mother died, but she was too distraught to offer helpful information, the sources said. She was taken twice to a Los Angeles hospital briefly after her mother's death, a source close to the family said last month.
Investigators have wrapped up the logistical part of their inquiry by having contacted all physicians and pharmacies with ties to Houston, and nothing so far appears criminal, the sources said.
Authorities are reviewing additional medical information that will be used in the final ruling on cause of death, and Houston's toxicology report should be complete "on or around" March 23, the sources said.
Last month, officials with the Los Angeles County coroner's office said the singer's body had no visible signs of trauma and foul play wasn't suspected. Her cause of death was listed as "deferred," officials said.
More official details on the investigation haven't been released because the Beverly Hills Police Department was granted a "security hold" on the case, the coroner's office said. Common in high-profile cases, the hold restricts the release of information.
Authorities have said that police and fire officials were called to Houston's hotel room after her unconscious body was found in the bathtub, just hours before she was to attend a pre-Grammy party.
A coroner official last month downplayed the suspicion that drugs had played a major role in Houston's death.
Assistant Chief Coroner Ed Winter said that "not many prescription bottles" were found in the singer's hotel room.
"I know there are reports that she maybe was drowned or did she overdose, but we won't make a final determination until all the tests are in," he said last month.