A toxicology report found marijuana, alcohol, "a cocaine-related substance," sedative and anti-anxiety medications and morphine in her system. Ahead of the full autopsy release, the medical examiner's office in Atlanta said that toxicology tests could not determine whether the morphine was the result of heroin use.
Released on what would have been Brown's 23rd birthday, the statement sheds light on her condition when she was found unresponsive in her bathtub on Jan. 21, 2015. (Brown spent months in the hospital, a rehabilitation center and hospice care until she died on July 26.)
Medical records, investigative files and other documents were used to determine how Brown died, according to officials.
"The underlying cause of death is the condition which starts the downhill course of events leading to death and in this case is the immersion associated with drug intoxication," the medical examiner's office said in the statement. "The pneumonia and encephalopathy are more immediate causes which resulted from the immersion and drug intoxication."
The medical examiner's office, however, was unable to determine whether the manner of Brown's death was intentional (a suicide or homicide) or accidental.
Previously, officials said her autopsy showed "no significant injuries" at the time of her "non-natural death," but a court order kept the information sealed.
In a statement released in July, the medical examiner's office indicated the months between the January incident and Brown's death would "complicate reconstruction of the events surrounding her initial unresponsiveness. Interpretation of autopsy findings and other information will also be challenging. However, an autopsy could be helpful to address questions which may arise about the cause of her unresponsiveness and eventual death."
Shareif Ziyadat / FilmMagic
Meanwhile, her boyfriend Nick Gordon, 20 – who was raised as the son of Brown's late mother Whitney Houston, but never officially adopted – is in the midst of a legal battle with Brown's family. A filing in a wrongful death lawsuit alleges Brown "died due to a violent altercation with Defendant (Gordon)" and that he "injected her with a toxic mixture" – claims that Gordon's lawyers vehemently denied. In a statement to PEOPLE last month, Gordon's legal counsel said he continued to "grieve privately" and was "dehumanized by the fictitious allegations."
Gordon posted on his Facebook Friday, "Happy Birthday baby girl!!" to commemorate what would have been Brown's 23rd birthday.
Source: Nick Gordon / Facebook
Brown's best friend and former roommate Mason Whitaker reflected on the loss of the late Houston and Bobby Brown's only child in an interview with PEOPLE in February.
"Not a day goes by that I don't think about her and the amazing influence she had on my life," Whitaker said after the one-year anniversary of her near-drowning. "Her vibrant spirit will live on forever. It devastates me to think the world won't be able to experience the amazing person she was."