Perugia, Italy (CNN) -- An Italian prosecutor in American Amanda Knox's appeal against her murder conviction put forward a vigorous defense in closing arguments Saturday of the DNA evidence used to find her guilty.
Prosecutor Manuela Comodi refuted testimony from independent forensics experts that cast doubt on the reliability of the evidence, insisting police forensic officers had handled the DNA material properly.
Comodi's appearance came on the second day of closing arguments for prosecutors in the appeal in the Italian city of Perugia.
Knox and her Italian ex-boyfriend Raffaele Sollecito are fighting to overturn their 2009 conviction for killing British student Meredith Kercher two years earlier. Knox was sentenced to 26 years in prison, while Sollecito got 25.
Knox, who wore her hair in a ponytail and a light blue short-sleeved shirt, appeared composed and attentive in court Saturday. Her parents were present for a second day, as the months-long process nears its conclusion.
The DNA evidence used to convict the pair has been scrutinized closely during the appeal, with particular attention paid to the knife used to kill Kercher and traces of DNA on her bra clasp.
Urging the jurors to uphold the convictions for Knox and Sollecito, Comodi defended the police investigation and sought to discredit the independent experts brought in to look at the evidence.
Their review had been "embarrassing, inappropriate, and presented in a hostile way" and was not based on science, she said.
The experts had been selective in what evidence they chose to review, Comodi charged, going on to list the other DNA evidence recovered from the villa where Kercher was found half-undressed and with her throat slit in November 2007.
She told jurors that the original court had concluded "beyond any reasonable doubt" that blood from both Knox and Kercher found in the bathroom sink had been left there when Knox washed herself after the killing.
The prosecutor also pointed to a partial footprint with Kercher's blood found on a bathroom mat, saying analysis had shown it was most likely to have been left by Sollecito, of the suspects.
He and Knox say they were at Sollecito's house on the night Kercher died, not the villa the two girls shared.
Comodi stressed that one of the independent experts, Carla Vecchiotti, was a professor rather than a professional in the field and said the police had better experience of a crime scene.
Vecchiotti and a second expert, Stefano Conti, argued in the summer that DNA evidence found on the knife used to kill Kercher and on her bra clasp was not reliable and had been contaminated by poor handling.
Prosecutors in 2009 said there were traces of Knox's genetic material on the handle and Kercher's in a tiny groove on the blade.
Comodi also questioned the testimony of another expert called by the defense, Carlo Torre, one of Italy's best-known forensics experts, who earlier this month cast doubt on the DNA evidence gathered from the knife.
Comodi then rejected the evidence given by expert Sara Gino, who said traces of Sollecito's DNA found on the bra clasp could have got there when Knox's and Kercher's clothes were together in the washing machine.
Comodi's statements followed the arguments Friday of appeals court prosecutor Giancarlo Costagliola and Giuliano Mignini, who prosecuted the first case.
Defense attorneys for Knox and Sollecito are expected to present their final arguments early next week.
Knox and Sollecito are appealing their convictions together, having been convicted in a joint trial. A third defendant, Rudy Guede, was convicted in a separate fast-track trial.
CNN's Hada Messia contributed to this report.