He later recognised the young woman as Amanda Knox, based on a picture of her, published on a newspaper following the murder. He also identified her in court.
However, he only made a statement about Knox's visit to his store, in November 2008, a year after the murder, at the prompting of a journalist, despite having been questioned by Inspector Volturno a few days after the murder. Nevertheless, it emerged that Volturno had only asked Quintavalle about purchases made by Raffaele Sollecito and not about Amanda Knox.
The Massei Court deemed that the testimony of Quintavalle was reliable, particularly because he gave a precise description of what he saw on the morning of November 2 and also provided a description of certain physical features of the woman he saw (light blue eyes and pale face) which, together with the unusual time, may well have fixed in his memory what Quintavalle said he saw (see the Massei Report. The court noted that Quintavalle's evidence contradicted statements by Amanda Knox that she was at Sollecito's house until about 10:30 am on the morning of November 2 (see, for example Knox's letter to the police and Amanda Knox's Testimony).
The Hellmann appeal did not re-examine Quintavalle but, nevertheless, discounted his testimony. The Hellmann Sentencing Report states that "even under the assumption that the circumstance is true, this would be a weak piece of circumstantial evidence, incapable in itself of proving guilt even presumptively; but in any case this Court holds that the testimony of the witness is not very reliable, in particular in what concerns the identification of the early‐ morning client with Amanda Knox."
The Supreme Court examined Hellmann's judgment on this point and was scathing (see English Summary of the Supreme Court of Cassation Motivation Report), stating that the Hellmann motivation is "vitiated by manifest illogicality, [...] since the information flows have not been correctly transposed by the Hellmann judges." The Supreme Court directed that "on this point, the new trial shall be conducted in light of the above considerations."
At Knox and Sollecito's re-convened appeal, in 2013, Judge Nencini re-examined Quintavalle's testimony and the arguments put forward against it by the defense. In his Sentencing Report he concludes, with regard to the testimonies of both Quintavalle and Antonio Curatolo:
"In conclusion of the examination of both of the testimonies [of Quintavalle and Curatolo], the Court holds that these same cannot in fact be classified as unreliable on the basis of arguments that are unproven and certainly at odds with an objective examination of their content; content which, for both testimonies, emerges as coherent, anchored for both witnesses to precise and telling reference points significant to both the witnesses, free of obvious contradictions and, in particular, made credible by the substantive disinterest of the witnesses with respect to the procedural fate of the defendants.
Thus, it can be affirmed at this point that, on the basis of the statements of both the witnesses, and on the basis of the picture emerging from the phone records previously noted, Amanda Marie Knox was lying when she was provided her second version of the events that occurred on the afternoon of 1 November and on the morning of 2 November 2007. The alibi provided by Amanda Marie Knox – of having returned to Raffaele Sollecito’s home in the late afternoon of 1 November 2007 and of having remained there, in the company of the co-accused, until 10:00am in the morning on 2 November 2007 – does not correspond to the truth."