AMERICAN STUDENT Amanda Knox won another battle in her quest to overturn a conviction for murdering her British roommate in Italy when an appeals court rejected a prosecutor’s request Wednesday for more DNA testing.

The decision is good for Knox because it means that an independent review of DNA evidence — previously ordered by the appeals court and hugely favorable to Knox — will stand. It deals a blow to the prosecutors who had sought to counter the results of that review, which harshly criticized how genetic evidence was used in the case.

The ruling by Judge Claudio Pratillo Hellmann also clears the way for closing arguments, which are set to begin Sept. 23 with the prosecution going first, followed by civil plaintiffs and the defense. Further retesting would have inevitably extended the 10-month long trial, now set to end late September or early October.

Knox’s father, Curt Knox, said his daughter started was seeing “the light at the end of the tunnel.”

However, Knox’s lawyer Luciano Ghirga warned that the court’s rejection of new DNA testing was not equal to a positive outcome of the whole appeals trial.

Knox was convicted in December 2009 of sexually assaulting and murdering her British roommate Meredith Kercher while they were studying in Perugia and sentenced to 26 years; Raffaele Sollecito, an Italian who was Knox’s boyfriend at the time, also was convicted and sentenced to 25 years.

Both have always maintained their innocence and are appealing the lower court’s verdict.

Without a clear motive or convincing witnesses, the DNA evidence is crucial, and much of the appeals outcome hinges on it.

In the first trial, prosecutors maintained that Knox’s DNA was found on the handle of a kitchen knife believed to be the murder weapon, and that Kercher’s DNA was found on the blade. They said Sollecito’s DNA was on the clasp of Kercher’s bra as part of a mixed trace that also included the victim’s genetic profile.

Those findings were always disputed by the defense and the appeals court agreed to nominate two independent experts to review the evidence. In a 145-page report, the experts found that much of that evidence was unreliable and possibly contaminated, that police had made glaring errors in evidence collecting and the below-standard testing raised doubts over the attribution of DNA traces.

The review was at the center of several fiercely debated hearings in the Perugia courtroom, with police and prosecutors defending the original investigation.

Pratillo Hellmann said the discussion had been thorough enough for the court to form an opinion. New testing would be “superfluous,” he said, rejecting the request made earlier in the day by Prosecutor Manuela Comodi.

The prosecutor said she was disappointed, though not surprised by the decision.

“One separates from one’s husband, and therefore one could certainly have separated from the wrong experts,” she told the ANSA news agency. Comodi had said in court that the experts were “inadequate” and “unreliable.”

The defense side said the prosecutors were simply moaning over a review that had not gone in their favor. They pointed out what they said was the “paradox” of a prosecution originally opposed to having new tests, now wanting more.

“It’s really kind of a desperation move on the prosecution to ask for another independent review that they originally were totally against,” Curt Knox said. “These were independent experts that the court appointed, so how many times do you need to have that done?”

Curt Knox said the court’s ruling showed “the judge and the jury believed in what the independent experts have brought back to them.” He is expected to be joined by Knox’s mother, Edda Mellas, for the last stage of the trial.

“Hopefully we’ll get to take Amanda home,” he said.

Francesco Maresca, a lawyer for the Kerchers, said the family would come to Perugia for the verdict, as they did in the first trial.

Just days ago, the family released a letter to express “great concern” over recent DNA evidence findings, asking the court to assess “every single (piece) of evidence, both scientific and circumstantial, as well as any witnesses who have taken the stand independently of any other information or media.”

They pointed out that there was more to the case than the DNA evidence that had been recently debated and lamented the “media frenzy” surrounding the case.

“My sister, a daughter brutally and selfishly taken from us nearing 4 years ago — and yet a not a single day goes by that we can grasp any peace or closure,” Stephanie Kercher, the victim’s sister, wrote.

Kercher was found stabbed to death on Nov. 2, 2007 in the apartment she shared with Knox. She had been murdered the night before, according to forensic police.

A third person, Rudy Hermann Guede of the Ivory Coast, also has been convicted of Kercher’s murder in a separate proceeding. Italy’s highest criminal court has upheld Guede’s conviction and his 16-year-prison sentence. Guede denies wrongdoing.

The court also rejected another prosecution request to put back on the stand a witness who had previously testified that his brother, a fugitive, had killed Kercher during a botched burglary. The witness, a jailed Naples mobster called Luciano Aviello, announced he wanted to retract and was questioned by Comodi in prison in July. The court ruled that transcriptions of that questioning would suffice.