Don't forget my sister Meredith was the real victim

The sister of Meredith Kercher urged that the murdered student should "not be forgotten" as the latest appeal by convicted killer Amanda Knox resumed today.

Stephanie Kercher was making her first public comments in more than 18 months since Knox, 24, was sentenced to 26 years in jail for the murder in Perugia, Italy.

In a letter to the family's Italian lawyer the Kerchers said that criticism of DNA evidence at the appeal had left them "seriously anxious and greatly troubled".

Stephanie wrote: "It is extremely difficult to understand how the results which were obtained with great care and presented in the first trial as valid could now be regarded as irrelevant."

The trial heard that a kitchen knife found in the flat of Knox's former boyfriend Raffaele Sollecito had her DNA on the handle and Ms Kercher's on the blade.

Two court-appointed experts have told the appeal that forensic scientists made errors handling the evidence and that the DNA from Ms Kercher on the blade was not enough to be re-examined.

Stephanie wrote: "How can the DNA on the knife be considered a small amount when the same experts cannot give an exact response to how much should be taken into consideration?

"It should also be remembered that both the prosecution and the defence had experts present when the original tests were carried out for the first trial at the forensic science lab in Rome.

"The defence seem to be focusing on these DNA aspects but we want for a moment to remember who this case is about: my sister, a daughter brutally taken away four years ago All those who are reading and writing about this case, please remember our beautiful Meredith." Miss Kercher, 21, of Coulsdon, was found semi naked and with her throat slit in the house she shared with Knox in November 2007.

Knox, an American student, and Sollecito, 27, from Italy, were convicted of murder and sex assault in December 2009. Their appeal began last year.

A video shown at the appeal showed scientists wearing dirty gloves putting evidence in plastic bags rather than paper bags, in breach of international protocol.

The appeal will break for 10 days on Saturday. A verdict is expected on about September 26.