How forensic failures and contaminated evidence led to wrongful convictions in one of Europe's most controversial murder cases
On November 1, 2007, British exchange student Meredith Kercher, 21, was murdered in the Perugia apartment she shared with American student Amanda Knox. Kercher was sexually assaulted and stabbed. Her half-naked body was discovered the following day after Knox and her boyfriend Raffaele Sollecito noticed blood in the bathroom and alerted police.
What followed was one of Europe's most controversial criminal investigations. Within days, Knox and Sollecito were arrested alongside Patrick Lumumba, a local bar owner. Knox, exhausted after hours of questioning, signed a statement implicating Lumumba—a confession she immediately retracted, claiming police pressure and fatigue. Lumumba was eventually exonerated. By December 2007, a third suspect emerged: Rudy Guede, who fled to Germany. His DNA matched a vaginal swab from Kercher, though he claimed consensual sex and said another man committed the murder.
In 2009, after a controversial trial, Knox was sentenced to 26 years in prison and Sollecito to 25 years. Knox had already served approximately four years when an appellate court reversed their convictions on October 3, 2011, finding them not guilty of murder and ordering their release.
Meredith Kercher found dead
The 21-year-old British student is found murdered in the apartment she shared with Amanda Knox in Perugia, Italy.
Knox and Sollecito arrested
Amanda Knox and her boyfriend Raffaele Sollecito are arrested and charged with murder, despite DNA evidence pointing to Rudy Guede.
Rudy Guede convicted
Rudy Guede, whose DNA was found throughout the crime scene, is convicted of Meredith Kercher's murder in a separate trial.
Knox and Sollecito convicted
Despite Guede's conviction, Knox and Sollecito are found guilty and sentenced to 26 and 25 years in prison respectively.
Acquittal in appeals court
After review of forensic evidence, Knox and Sollecito are acquitted. Knox returns to the US after four years in prison.
But the case was far from over. In January 2014, a retrial conviction shocked observers when an appeals court again found Knox and Sollecito guilty. However, Italy's Supreme Court of Cassation intervened. On March 27, 2015, the nation's highest court issued a definitive ruling: Knox and Sollecito were innocent, the convictions overturned permanently.
The Supreme Court's decision exposed critical failures in the investigation and prosecution. The court cited "sensational failures" in forensic handling and "culpable omissions" by lower courts in ignoring evidence of contamination.
The forensic evidence against Knox was problematic from the start. No DNA profiles belonging to Knox were found in the murder room. A knife allegedly used in the crime, taken from Sollecito's kitchen, contained only a low-level trace of Kercher's DNA on the blade—with no blood present. Knox's DNA appeared on the handle, consistent with innocent kitchen use. A 2011 court review found no evidential trace of Kercher's and identified basic errors in handling.
New conviction
An Italian court overturns the acquittal and convicts Knox and Sollecito again, this time in absentia.
Final exoneration
Italy's Supreme Court definitively acquits Amanda Knox and Raffaele Sollecito after eight years of legal battle.
Rudy Guede released
The actual perpetrator, Rudy Guede, is released after serving 13 years of his 16-year sentence.
More damaging to the prosecution's case: Sollecito's DNA on Kercher's bra clasp, central to the case against him, came from a clasp that had gone missing for 47 days before reappearing—a gap suggesting severe contamination risk. Court-appointed experts testified to this contamination likelihood. The clasp bore DNA fragments from multiple males, further undermining its evidentiary value.
Additionally, investigators found no phone calls, text messages, or digital communication between Knox, Sollecito, and Guede—evidence that would be expected if the three had coordinated the crime. The Supreme Court noted a "material non-existence" of evidence supporting their involvement as a trio. Inconsistencies in Knox and Sollecito's statements, the court determined, did not prove false alibis.
Rudy Guede remains the sole person convicted of Kercher's murder, having proceeded through a separate, faster trial. His conviction stands.
While Knox's defamation conviction for falsely implicating Lumumba was upheld in 2015, the court deemed her three-year sentence already served through prior imprisonment.
The Amanda Knox case stands as a cautionary tale about forensic mishandling, investigative tunnel vision, and the potential for wrongful conviction in high-profile cases. Knox's exoneration came only after years of legal battles and significant reputational damage.
**Sources**
https://en.wikipedia.org/wiki/Amanda_Knox
https://pubmed.ncbi.nlm.nih.gov/26971315/
https://famous-trials.com/amanda-knox/2634-the-amanda-knox-case-a-chronology
https://www.aetv.com/articles/amanda-knox-case-timeline