Julia Roberts' half-sister left a ''ranting'' note which reportedly claimed the actress ''drove her'' to suicide.
Nancy Motes - who had a difficult relationship with the Oscar-winning star - was found dead on Sunday (09.02.14) and insiders investigating her passing say she ''definitely'' took her own life.
A source told the New York Daily News newspaper:
''It was definitely a suicide. She left a five-page suicide letter. The EMT found it.
''There were three pages of rantings that her sister drove her to do this. There was one page to her mom, telling her how much she loved her, and one page apologising to [her fiancé John Dilbeck].''
Nancy - the daughter of Julia's mother, Betty Lou, and stepfather, Michael Motes - was found by her fiance in the bathtub of a Los Angeles' house she was pet-sitting at and her body may have lain undiscovered for up to 12 hours.
The source added: ''It looks like a pill overdose.''
Before her death, Nancy made a series of tweets attacking her famous relative, who she fell out with last summer after giving a tell-all interview.
In one post last month, she wrote: ''So my 'sister' said that with all her friends & fans she doesn't need any more love. Just so you all know 'America's Sweetheart' is a B***h!!'(sic)''
And a later tweet read: ''Do you want to be a fan of someone so cruel? She's not even that good of an actress. Happy you totally F***ed with me? (sic)''
The messages have now been removed from the social networking site.
Coroner's spokesman Ed Winter confirmed there was a suicide note found but said he didn't believe it ran to eight pages.
An autopsy was completed yesterday (11.02.14), but the cause of death has been deferred until additional toxicology tests are carried out.