Kercher family left with just a question: who killed Meredith?

Truth about murder remains elusive, with even the existence of a second assailant now in doubt. Peter Popham reports

If Amanda Knox and Raffaele Sollecito did not murder Meredith Kercher, then who did?

This was the plaintive question raised by Ms Kercher's brother Lyle at a press conference in Perugia yesterday. The exoneration of the former lovers – freed, as the court baldly put it, because they did not commit the crime – leaves the victim's family in limbo. The decision of the first court in the same courtroom two years ago was "emphatic," Mr Kercher said. "If those two are not the guilty parties, then who are the guilty people?" he asked. "We feel like we are back to square one and the search goes on for what really happened."

The misery of Ms Kercher's family is easy to understand. At the original trial prosecutor Giuliano Mignini presented a tableau that was horribly vivid: the young couple and the drug-pusher and drifter Rudy Guede killing Meredith at the culmination of a depraved "Hallowe'en rite". Local and international media took the hint from his informal briefings to tell a lurid tale of sex, drugs and orgy. Remove Ms Knox and Mr Sollecito from that account of what took place, and what remains?

According to Paul Ciolino, an American private investigator hired by Ms Knox's supporters who published an exhaustive examination of the investigation and trial in January last year, the idea that more than one person was involved in Ms Kercher's murder never had any basis in fact.

On the day her body was discovered, her bedroom was liberally littered with Rudy Guede's traces: his DNA on the victim, her clothing and handbag; his bloody shoeprints and fingerprints in the room.

If prosecutor Mignini's thesis was correct and all three were involved in the murder – which involved the copious shedding of blood – how was it possible that there were no comparable traces of them in the room as well? Yet no such traces of either Ms Knox or Mr Sollecito were found there – no DNA, no prints, nothing to substantiate the prosecution's description.

Ms Knox and Mr Sollecito were eventually nailed to the crime scene by Ms Kercher's bra clasp, on which investigators claimed to have found Mr Sollecito's DNA. The kitchen knife found in his flat had Ms Knox's fingerprints on the handle and, it was alleged, Ms Kercher's DNA on the tip.

This was the only forensic evidence against them, and when independent experts dismissed those claims at the appeal that finished this week, there was nothing left. Attention therefore inevitably shifts from "whodunnit" – the guilty man is serving 16 years in jail – to how the orgy scenario was arrived at.

Ms Knox and Mr Sollecito were photographed behaving in ways considered "suspicious" – not weeping copiously but embracing and kissing – in the hours after the murder. In their first interviews with the police, both maintained separately that they had spent the night of the murder in Mr Sollecito's flat, alone. But when Ms Knox was subjected to an all-night interrogation on 5-6 November, a new figure entered the picture.

On her mobile phone was an exchange of messages with Patrick Lumumba, the Congolese man who had lived in Perugia for a decade and ran a bar where she worked part time. He sent her a message on the evening of 1 November, telling her not to bother coming in to work – business was slack. She replied, briefly: "See you later."

Police interpreted "see you later" to mean, not, "see you some time" but see you later this evening. It meant they had an assignation. According to Mignini, they arranged to meet at the house that Amanda and Meredith shared.

The entry of the hapless Congolese into the picture was crucial to the investigation. Hairs belonging to a black person had been found in the victim's left hand. Ms Knox and Mr Sollecito's innocent embraces, her innocuous exchange of text messages with Lumumba, and the strands of black hair were now put together to indicate an orgy involving all three.

Two weeks after the murder, when Lumumba turned out to have a good alibi, and it was found that Guede's hair matched that recovered from the scene, one black man was extracted from the case and the second put in his place. During both the first trial and the appeal, defence and prosecution have quarrelled over the interpretation of the wounds inflicted on Ms Kercher, the prosecution insisting that the claimed absence of "defensive" wounds to the hands meant she had been pinioned by two people while a third wielded the knife. Guede himself claimed that a second person – a man, according to his first, recorded phone call on the question – wielded the knife. His motive for saying so was clear: to shield himself from ultimate blame.