Bobbi Kristina Brown Used Heroin, Other Drugs Before Being Found in Bathtub, Source Says

Bobbi Kristina Brown was under the influence of drugs the morning she was found unresponsive in her bathtub, a source familiar with the details of the situation tells PEOPLE.

The 21-year-old was found face-down and unresponsive in the tub inside her Georgia home on Jan. 31. She was rushed to the hospital and has been on life support in critical condition ever since.

Multiple sources who know Brown confirm to PEOPLE that she regularly used heroin, cocaine and Xanax in recent months. She was also a heavy drinker, the sources say. One of the sources who saw Brown regularly says she often appeared to be high, slurring her words and seeming incoherent.

Another source says Brown had been “in and out” of rehab in the three years since her mother died. Brown was “distraught” over the anniversary of her mother’s death on Feb. 11, which fueled her addiction despite attempts at recovery, the source adds.

“How thin she had gotten is an indicator,” the source says. “This girl was trying hard, but she didn’t have any support system. She was still dealing with a lot of grief over her mother.”

Like her daughter, Whitney Houston was found unresponsive in a bathtub with drugs in her system. Houston was inside the Beverly Hilton Hotel in February 2012 when she died. An autopsy later revealed she had cocaine in her system.

In 2011, Bobbi Kristina’s father, Bobby Brown, spoke to PEOPLE about his own drug use, admitting to using heroin and cocaine before getting clean. He said he was inspired to get off drugs partly after watching his reality show, Being Bobby Brown, which included tumultuous family scenes.

•Reporting by ELISSA ROSEN and K.C. BAKER