Slash's 25-year-old stepdaughter, Lucy-Bleu Knight, left notes for her family before she died by suicide at a Los Angeles residence on July 19.
"A packet of suicide notes was found on a side table in the main room," read a coroner report obtained by The Post on Monday.
"According to family, she had no previous suicide attempts but did have prior ideations."
Knight also had "a history of undiagnosed mental illness," with her family stating she "was paranoid and would have hallucinations," per the report.
In 2024, she was hospitalized twice on 5150 holds, which means an adult experiencing a mental health crisis is involuntarily detained for 72 hours, per the OC Health Care Agency.
According to the report, Knight's body was recovered from the bathroom of the Los Angeles Airbnb she booked for four days. She was scheduled to check out on July 15.
The property manager attempted to message Knight many times and was "unable to access the front door" of the home before calling emergency services.
When officers arrived on July 19, they "noticed resistance they described as 'suction' when opening the front door of the unit."
"Upon opening the locked door, Officers observed a hand-written sign apparently meant for first responders warning about toxic gas," the report continued.
"A chemical scent was also detected by Officers, who immediately backed out of the residence and called for assistance."
At the scene, the Fire Department Squad 87 Hazmat Unit recovered lethal doses of sulfuric acid, hydrochloric acid, cerium hydroxide and sodium thiosulfate.
Antidepressants, including escitalopram, were also found in Knight's wallet.
Knight's cause of death was determined to be hydrogen sulfide toxicity. The inflammable gas can be fatal when a person is exposed for a long period, per the Centers for Disease Control and Prevention.
Slash, 59, mourned his stepdaughter via Instagram on July 21, saying she "passed away peacefully."
"Lucy-Bleu was a talented artist, a passionate dreamer, and a charming, lovable, sweet soul," the Guns N' Roses guitarist wrote.
At the time, he asked fans for privacy and not to speculate about her cause of death as "they grieve and process this devastating loss."