On the evening of the murder, he was sitting in his habitual place, smoking and reading a magazine. According to his later statements, he looked up several times and recognised Amanda Knox and Raffaele Sollecito in the Piazza, between 9:30pm and midnight, in contradiction to their witness statements.
Judge Massei (in The Massei Report) noted that Curatolo had "a way of life different from the usual one" but pointed out that one's "way of living one’s life does not affect one's ability to perceive events and be able to report them". He found Curatolo's evidence credible.
At Knox and Sollecito's appeal, Judge Hellmann rejected Curatolo's evidence, mentioning the deterioration of his intellectual faculties, since the trial; his lifestyle and habits; his heroin addiction; and his ambiguity (by his appearance in 2011) about which day he saw Knox and Sollecito. See The Hellmann Sentencing Report
Curatolo was convicted of possessing heroin in 2011 and died in prison in May 2012.
The Supreme Court of Cassation were scathing of Hellmann's conclusions, describing his analysis of Curatolo's testimony, as "absolutely reprehensible", and a "manifest failure of the assumption of a thorough examination of the data and circumstances". (See English Summary of the Supreme Court of Cassation Motivation Report).
At Knox and Sollecito's second appeal, in 2013, Judge Nencini carefully considered the evidence given by Curatolo at the original trial and at the annulled Hellmann appeal. He devotes several pages of his Sentencing Report to transcribing parts of the testimony and discussing its merits. He echoes the Supreme Court judgment in noting that the Court must not make "a judgment of the witness’s reliability on the basis of anthropological assessments" and states that Curatolo's testimony "must be evaluated on the basis of the ordinary interpretative criteria of evaluation that the criminal Court employs in every proceeding". Nencini concludes:
"Mr. Curatolo’s testimony, in conclusion, must be evaluated by this Court together with all the other circumstantial evidence that emerges and that leads us to conclude that the alibi provided by Amanda Marie Knox and affirmed by Raffaele Sollecito is an unfounded alibi."