Amanda Knox has sent a letter of support to Lucy Letby in prison as well as a copy of her memoir 'Free'.
The 38-year-old American revealed her backing for the convicted child killer during a Q&A about her latest documentary, Mouth Of The Wolf.
Directed by her husband, Christopher Robinson, the film follows her return to Perugia in Italy, where British student Meredith Kercher was murdered in 2007.
But the promotional trip to London is said to have left the Kercher family 'speechless', with their lawyer accusing Ms Knox of 'cashing in' on Meredith's memory.
Ms Knox - who was twice convicted and acquitted over the death of her 21-year-old flatmate - fought back tears on Tuesday night as she spoke at Greenwich Picturehouse in London.
There, she revealed her attempt to befriend former neonatal nurse Letby, 36, who is serving life in prison for the murder of seven infants and the attempted murder of seven others.
Mother-of-two Ms Knox said: 'I did send her a copy of my book. I wrote a letter to her.
'I wrote a letter to her parents as well. But I have not talked to her personally.'
Amanda Knox revealed her backing for the convicted child killer Lucy Letby during a Q&A about her latest documentary, Mouth Of The Wolf
Lucy Letby has reportedly received a copy of Ms Knox's book Free - published last year - which details her life after jail, focusing on the aftermath of her acquittal. She also wrote a book in 2013 titled Waiting To Be Heard
She continued: 'You do not need a smoking gun of innocence to say a conviction is unsafe. You do not need to know someone is 100 per cent innocent to say they should not be in prison.'
Ms Knox's book Free - published last year - details her life after jail, focusing on the aftermath of her acquittal. She also wrote a book in 2013 titled Waiting To Be Heard.
Discussing her podcast about Letby and controversies surrounding her case, Ms Knox said: 'It is not about her as a person - it's about the facts of the case and what we can actually know.'
She added that people 'aren't really about evidence' but rather how it 'makes them feel'. An audience member who spoke with Ms Knox revealed to the Daily Mail that she told Letby to hold on to 'hope'.
The Kercher family lawyer, Francesco Maresca, accused Ms Knox of 'cashing in for the umpteenth time on Meredith's memory' and said the family felt 'enough is enough'.