Peaches Geldof died from a heroin overdose, an inquest is reportedly expected to show.
The British model and TV presenter was found dead in her home south of London on April 7 while caring for her 11-month-old son.
Police described the 25-year-old's death as "non-suspicious", and an autopsy days later was inconclusive.
But toxicology results due to be released on Thursday will show the mother of two died from a heroin overdose, the Times of London reported late on Wednesday.
The inquest into Geldof's death will begin with a brief inquest hearing on Thursday, at which a senior police officer will read a statement and the coroner will release the results of a post-mortem investigation.
Geldof leaves behind her husband, musician Tom Cohen, and two young sons.
She is the daughter of Irish singer and songwriter Bob Geldof and Paula Yates, who died of a heroin overdose in 2000.
