The case against American student Amanda Knox in the 2007 murder of her British housemate contained no gaps or inconsistencies, Italian judge Giancarlo Massei wrote in a legal opinion published Thursday.
Evidence presented during the year-long trial gave a "comprehensive and solid picture, without gaps or inconsistencies" leading to guilty verdicts for Knox and her then-boyfriend Raffaele Sollecito, Massei wrote, according to the ANSA news agency.
Knox, now 22, and Sollecito, an Italian engineering student who is now 25, were convicted of murdering Meredith Kercher, 21, in a drug-fueled sex game that turned violent on the night of Nov. 1, 2007, in the university town of Perugia, in central Italy.
A third person, 23-year-old Rudy Guede, from the Ivory Coast, was convicted separately in the case under a fast-track procedure.
Kercher was found semi-nude in a pool of blood under a duvet with multiple stab wounds to the neck in her room in the cottage she shared with Knox and two other women, who were away for a long holiday weekend.
The sensational murder was carried out "with no planning, no animosity or rancor against the victim," Massei wrote in the 427-page opinion issued three months after the verdict and also signed by co-judge Beatrice Cristiani.
The crime came about because of a combination of "purely random" circumstances, notably that both Knox and Sollecito were free that evening, they ran into Guede and went to the house where Kercher was alone, it said.
The opinion also asserted that Knox "freely accused Patrick Diya Lumumba of having killed Meredith and accused him knowing of (his) innocence."
Knox was sentenced to 26 years in jail, while Sollecito got 25 years.
The extra year for Knox was punishment for defaming bar owner and musician Lumumba, of the Democratic Republic of Congo, said Massei during the sentencing.
Lumumba spent two weeks in jail before being released for lack of evidence.
Guede's initial sentence of 30 years was slashed to 16 on appeal in late December.
Both Knox and Sollecito, who were jailed less than a week after the murder, were appealing their convictions.
The Italian court came under harsh criticism from many who felt Knox, a native of Seattle, was convicted only on circumstantial evidence and that the Italian press, which jurors were free to read, assassinated her character.
A diplomatic furor arose after the verdict prompted a senator from Washington state to charge that Italy's judicial system was flawed.
U.S. Secretary of State Hillary Clinton initially said she would meet with Senator Maria Cantwell "or anyone who has a concern" over the conviction.
But Clinton's spokesman said soon afterward that the U.S. government had no "indications ... that Italian law was not followed."