An emotional Amanda Knox has castigated the media for depicting her as a “dirty man-eater” when she was on trial for the murder of the British student Meredith Kercher.

Knox, now 31, was twice convicted and twice acquitted of killing Kercher, 21, in the home they shared in the Italian university town of Perugia in November 2007.

She returned to Italy this week for the first time since being released from prison in 2011, to participate in a debate entitled “Trial by Media” at the Criminal Justice festival in Modena.

Earlier this week, the Kerchers’ lawyer, Francesco Maresca, said Knox’s public appearances were painful for the family.

“All these insistences and appearances are only ever done to keep the attention on herself,” Maresca said. “The murder is a tragic memory for the Kercher family. They lost their daughter and sister in such a terrible way. It’s also an injustice for them as they still don’t know the full truth.”

He said Knox’s return to Italy and involvement in the conference was inappropriate, adding: “It’s unjustified because her process was not a classic case of ‘judicial error’. There was a swing in the decisions: some judges decided one way, and others in another way.”

Knox, who had always declared her innocence, spoke about the moment she was found guilty for the first time and sentenced to 26 years in jail in 2009.

“My innocence didn’t save me because the media created a story … and people liked that story,” she told a packed room on Saturday. “I was the dirty man-eater, Foxy Knoxy.”

She accused the media of producing “clickbait” stories while she was imprisoned instead of examining the evidence of the case. She also spoke about her family being tormented by the press.

“I wasn’t innocent until proven guilty, I was a wise, drugged-up whore – it was unfounded but it awoke people’s imagination. These sensational and defamatory images also entered the courtroom. The investigation was contaminated and the jury corrupted. It was impossible for me to have a fair trial.”

Knox added: “On 1 November 2007 the robber Rudy Guede entered the house and raped and killed my housemate Meredith. His DNA was left and then he escaped the country. He was tried and convicted. But despite all the attention [on the case] hardly anyone heard of the name Rudy Guede, because all of the focus was on me.”

The body of Kercher, a student from Coulsdon, Surrey, who was in Italy on an Erasmus programme, was found under a duvet in her bedroom, partly undressed with multiple stab wounds.

Knox and her ex-boyfriend, Raffaele Sollecito, spent four years in prison after initially being convicted of the murder. For Knox, three of those years were for a defamation conviction after she wrongly accused Patrick Lumumba, a bar owner, of the crime. Lumumba spent two weeks in jail and was released after someone came forward with an alibi for him. Knox had told investigators that she “covered her ears as he [Lumumba] killed”. She later said she had made the allegation under police coercion.

On Saturday she said she had retracted the accusation hours after making it, but had been ignored by the police.

“They arrested Patrick, Raffaele and I,” she said. “The next day they organised a press conference to say that the case is closed.”

Carlo Pacelli, the lawyer who represented Lumumba, told the Observer his client had not received any compensation over the defamation.

“Patrick was the victim of slander [by] Amanda Knox and for this she was given a three-year term for accusing a man she knew was innocent,” Pacelli said.

“She also never apologised to him,” he claimed. “It’s shameful.”

Knox and Sollecito were acquitted in 2011 before being convicted again in 2014 by the Florence appeals court, which ruled that the extent of the injuries inflicted on Kercher was such that Guede, the Ivorian man serving time for the murder, could not have acted alone. Italy’s highest court quashed the convictions in a definitive ruling in 2015 because of “stunning flaws” in the investigation.

Eight years on, Italy asks: so who were Meredith Kercher’s killers? Read more

Italy Innocence Project, the event organiser, has been criticised for inviting Knox to take part.

“She was invited as she is an icon of trial by media,” said Guido Sola, a lawyer with the organisation. “Knox is a free person who is speaking about being slammed on the front pages and having her privacy violated.”

Knox described Kercher as a “brilliant girl” whose friendship she had enjoyed for “a very short time”, and expressed her condolences to the family.

The Kercher family rarely respond to the publicity generated by Knox, who reportedly earned £3.5m for her memoir, took part in a Netflix documentary about the case in 2016 and has been the subject of other books and films.

“No system is perfect and this case wasn’t perfectly done,” she said. “There was a lot of confusion and the Kercher family had to live with this anxiety … with false information … I am sorry for them. But the assassin is in jail.”