Knox and Kercher were college exchange students - Knox from Seattle, Kercher from the UK - when Meredith was foun murdered in the Italian house they shared.
Knox was convicted of the killing in 2009, along with then-boyfriend Raffaelo Sollecito and another man. Kercher's sister Stephanie railed against her appeal.
Amanda Knox claims the DNA evidence used against her was unreliable.
In a letter released by her family's Italian lawyer, Stephanie Kercher, says:
"In these last few weeks we have been left seriously anxious and greatly troubled by the news regarding the original DNA findings in the case."
'It is extremely difficult to understand how the results, obtained with great care and presented in the first trial as valid, could now be regarded as irrelevant."
As part of her appeal, new DNA experts were brought in, with some experts claiming evidence used to convict Knox was unreliable and should be excluded.
